Interface Buffer

Hierarchy

Uint8Array
- Buffer

Index

Methods

compare copy entries equals fill includes indexOf keys lastIndexOf readBigInt64BE readBigInt64LE readBigUInt64BE readBigUInt64LE readBigUint64BE readBigUint64LE readDoubleBE readDoubleLE readFloatBE readFloatLE readInt16BE readInt16LE readInt32BE readInt32LE readInt8 readIntBE readIntLE readUInt16BE readUInt16LE readUInt32BE readUInt32LE readUInt8 readUIntBE readUIntLE readUint16BE readUint16LE readUint32BE readUint32LE readUint8 readUintBE readUintLE reverse slice subarray swap16 swap32 swap64 toJSON toString values write writeBigInt64BE writeBigInt64LE writeBigUInt64BE writeBigUInt64LE writeBigUint64BE writeBigUint64LE writeDoubleBE writeDoubleLE writeFloatBE writeFloatLE writeInt16BE writeInt16LE writeInt32BE writeInt32LE writeInt8 writeIntBE writeIntLE writeUInt16BE writeUInt16LE writeUInt32BE writeUInt32LE writeUInt8 writeUIntBE writeUIntLE writeUint16BE writeUint16LE writeUint32BE writeUint32LE writeUint8 writeUintBE writeUintLE

Methods

compare

compare(target: Uint8Array, targetStart?: number, targetEnd?: number, sourceStart?: number, sourceEnd?: number): 0 | 1 | -1
Compares buf with target and returns a number indicating whether bufcomes before, after, or is the same as target in sort order. Comparison is based on the actual sequence of bytes in each Buffer.
- 0 is returned if target is the same as buf
- 1 is returned if target should come beforebuf when sorted.
- -1 is returned if target should come afterbuf when sorted.
```
import { Buffer } from 'buffer';

const buf1 = Buffer.from('ABC');
const buf2 = Buffer.from('BCD');
const buf3 = Buffer.from('ABCD');

console.log(buf1.compare(buf1));
// Prints: 0
console.log(buf1.compare(buf2));
// Prints: -1
console.log(buf1.compare(buf3));
// Prints: -1
console.log(buf2.compare(buf1));
// Prints: 1
console.log(buf2.compare(buf3));
// Prints: 1
console.log([buf1, buf2, buf3].sort(Buffer.compare));
// Prints: [ <Buffer 41 42 43>, <Buffer 41 42 43 44>, <Buffer 42 43 44> ]
// (This result is equal to: [buf1, buf3, buf2].)
```
The optional targetStart, targetEnd, sourceStart, and sourceEndarguments can be used to limit the comparison to specific ranges within targetand buf respectively.
```
import { Buffer } from 'buffer';

const buf1 = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8, 9]);
const buf2 = Buffer.from([5, 6, 7, 8, 9, 1, 2, 3, 4]);

console.log(buf1.compare(buf2, 5, 9, 0, 4));
// Prints: 0
console.log(buf1.compare(buf2, 0, 6, 4));
// Prints: -1
console.log(buf1.compare(buf2, 5, 6, 5));
// Prints: 1
```
ERR_OUT_OF_RANGE is thrown if targetStart < 0, sourceStart < 0,targetEnd > target.byteLength, or sourceEnd > source.byteLength.
Parameters
- target: Uint8Array
  
  A Buffer or Uint8Array with which to compare buf.
- Optional targetStart: number
  
  The offset within target at which to begin comparison.
- Optional targetEnd: number
  
  The offset within target at which to end comparison (not inclusive).
- Optional sourceStart: number
  
  The offset within buf at which to begin comparison.
- Optional sourceEnd: number
  
  The offset within buf at which to end comparison (not inclusive).
Returns 0 | 1 | -1
compare(target: Uint8Array, targetStart?: number, targetEnd?: number, sourceStart?: number, sourceEnd?: number): 0 | 1 | -1
Compares buf with target and returns a number indicating whether bufcomes before, after, or is the same as target in sort order. Comparison is based on the actual sequence of bytes in each Buffer.
- 0 is returned if target is the same as buf
- 1 is returned if target should come beforebuf when sorted.
- -1 is returned if target should come afterbuf when sorted.
```
import { Buffer } from 'buffer';

const buf1 = Buffer.from('ABC');
const buf2 = Buffer.from('BCD');
const buf3 = Buffer.from('ABCD');

console.log(buf1.compare(buf1));
// Prints: 0
console.log(buf1.compare(buf2));
// Prints: -1
console.log(buf1.compare(buf3));
// Prints: -1
console.log(buf2.compare(buf1));
// Prints: 1
console.log(buf2.compare(buf3));
// Prints: 1
console.log([buf1, buf2, buf3].sort(Buffer.compare));
// Prints: [ <Buffer 41 42 43>, <Buffer 41 42 43 44>, <Buffer 42 43 44> ]
// (This result is equal to: [buf1, buf3, buf2].)
```
The optional targetStart, targetEnd, sourceStart, and sourceEndarguments can be used to limit the comparison to specific ranges within targetand buf respectively.
```
import { Buffer } from 'buffer';

const buf1 = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8, 9]);
const buf2 = Buffer.from([5, 6, 7, 8, 9, 1, 2, 3, 4]);

console.log(buf1.compare(buf2, 5, 9, 0, 4));
// Prints: 0
console.log(buf1.compare(buf2, 0, 6, 4));
// Prints: -1
console.log(buf1.compare(buf2, 5, 6, 5));
// Prints: 1
```
ERR_OUT_OF_RANGE is thrown if targetStart < 0, sourceStart < 0,targetEnd > target.byteLength, or sourceEnd > source.byteLength.
Parameters
- target: Uint8Array
  
  A Buffer or Uint8Array with which to compare buf.
- Optional targetStart: number
  
  The offset within target at which to begin comparison.
- Optional targetEnd: number
  
  The offset within target at which to end comparison (not inclusive).
- Optional sourceStart: number
  
  The offset within buf at which to begin comparison.
- Optional sourceEnd: number
  
  The offset within buf at which to end comparison (not inclusive).
Returns 0 | 1 | -1

copy

copy(target: Uint8Array, targetStart?: number, sourceStart?: number, sourceEnd?: number): number

Copies data from a region of buf to a region in target, even if the targetmemory region overlaps with buf.

TypedArray.prototype.set() performs the same operation, and is available for all TypedArrays, including Node.js Buffers, although it takes different function arguments.

import { Buffer } from 'buffer';

// Create two `Buffer` instances.
const buf1 = Buffer.allocUnsafe(26);
const buf2 = Buffer.allocUnsafe(26).fill('!');

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

// Copy `buf1` bytes 16 through 19 into `buf2` starting at byte 8 of `buf2`.
buf1.copy(buf2, 8, 16, 20);
// This is equivalent to:
// buf2.set(buf1.subarray(16, 20), 8);

console.log(buf2.toString('ascii', 0, 25));
// Prints: !!!!!!!!qrst!!!!!!!!!!!!!

import { Buffer } from 'buffer';

// Create a `Buffer` and copy data from one region to an overlapping region
// within the same `Buffer`.

const buf = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf[i] = i + 97;
}

buf.copy(buf, 0, 4, 10);

console.log(buf.toString());
// Prints: efghijghijklmnopqrstuvwxyz

Returns

The number of bytes copied.

Parameters

target: Uint8Array

A Buffer or Uint8Array to copy into.
Optional targetStart: number

The offset within target at which to begin writing.
Optional sourceStart: number

The offset within buf from which to begin copying.
Optional sourceEnd: number

The offset within buf at which to stop copying (not inclusive).

Returns number

copy(target: Uint8Array, targetStart?: number, sourceStart?: number, sourceEnd?: number): number

Copies data from a region of buf to a region in target, even if the targetmemory region overlaps with buf.

TypedArray.prototype.set() performs the same operation, and is available for all TypedArrays, including Node.js Buffers, although it takes different function arguments.

import { Buffer } from 'buffer';

// Create two `Buffer` instances.
const buf1 = Buffer.allocUnsafe(26);
const buf2 = Buffer.allocUnsafe(26).fill('!');

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

// Copy `buf1` bytes 16 through 19 into `buf2` starting at byte 8 of `buf2`.
buf1.copy(buf2, 8, 16, 20);
// This is equivalent to:
// buf2.set(buf1.subarray(16, 20), 8);

console.log(buf2.toString('ascii', 0, 25));
// Prints: !!!!!!!!qrst!!!!!!!!!!!!!

import { Buffer } from 'buffer';

// Create a `Buffer` and copy data from one region to an overlapping region
// within the same `Buffer`.

const buf = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf[i] = i + 97;
}

buf.copy(buf, 0, 4, 10);

console.log(buf.toString());
// Prints: efghijghijklmnopqrstuvwxyz

Returns

The number of bytes copied.

Parameters

target: Uint8Array

A Buffer or Uint8Array to copy into.
Optional targetStart: number

The offset within target at which to begin writing.
Optional sourceStart: number

The offset within buf from which to begin copying.
Optional sourceEnd: number

The offset within buf at which to stop copying (not inclusive).

Returns number

entries

entries(): IterableIterator<[number, number]>

Creates and returns an iterator of [index, byte] pairs from the contents of buf.

import { Buffer } from 'buffer';

// Log the entire contents of a `Buffer`.

const buf = Buffer.from('buffer');

for (const pair of buf.entries()) {
  console.log(pair);
}
// Prints:
//   [0, 98]
//   [1, 117]
//   [2, 102]
//   [3, 102]
//   [4, 101]
//   [5, 114]

Returns IterableIterator<[number, number]>

entries(): IterableIterator<[number, number]>

Creates and returns an iterator of [index, byte] pairs from the contents of buf.

import { Buffer } from 'buffer';

// Log the entire contents of a `Buffer`.

const buf = Buffer.from('buffer');

for (const pair of buf.entries()) {
  console.log(pair);
}
// Prints:
//   [0, 98]
//   [1, 117]
//   [2, 102]
//   [3, 102]
//   [4, 101]
//   [5, 114]

Returns IterableIterator<[number, number]>

equals

equals(otherBuffer: Uint8Array): boolean

Returns true if both buf and otherBuffer have exactly the same bytes,false otherwise. Equivalent to buf.compare(otherBuffer) === 0.

import { Buffer } from 'buffer';

const buf1 = Buffer.from('ABC');
const buf2 = Buffer.from('414243', 'hex');
const buf3 = Buffer.from('ABCD');

console.log(buf1.equals(buf2));
// Prints: true
console.log(buf1.equals(buf3));
// Prints: false

Parameters

otherBuffer: Uint8Array

A Buffer or Uint8Array with which to compare buf.

Returns boolean

equals(otherBuffer: Uint8Array): boolean

Returns true if both buf and otherBuffer have exactly the same bytes,false otherwise. Equivalent to buf.compare(otherBuffer) === 0.

import { Buffer } from 'buffer';

const buf1 = Buffer.from('ABC');
const buf2 = Buffer.from('414243', 'hex');
const buf3 = Buffer.from('ABCD');

console.log(buf1.equals(buf2));
// Prints: true
console.log(buf1.equals(buf3));
// Prints: false

Parameters

otherBuffer: Uint8Array

A Buffer or Uint8Array with which to compare buf.

Returns boolean

fill

fill(value: string | number | Uint8Array, offset?: number, end?: number, encoding?: BufferEncoding): "buffer".Buffer
Fills buf with the specified value. If the offset and end are not given, the entire buf will be filled:
```
import { Buffer } from 'buffer';

// Fill a `Buffer` with the ASCII character 'h'.

const b = Buffer.allocUnsafe(50).fill('h');

console.log(b.toString());
// Prints: hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
```
value is coerced to a uint32 value if it is not a string, Buffer, or integer. If the resulting integer is greater than 255 (decimal), buf will be filled with value & 255.

If the final write of a fill() operation falls on a multi-byte character, then only the bytes of that character that fit into buf are written:
```
import { Buffer } from 'buffer';

// Fill a `Buffer` with character that takes up two bytes in UTF-8.

console.log(Buffer.allocUnsafe(5).fill('\u0222'));
// Prints: <Buffer c8 a2 c8 a2 c8>
```
If value contains invalid characters, it is truncated; if no valid fill data remains, an exception is thrown:
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(5);

console.log(buf.fill('a'));
// Prints: <Buffer 61 61 61 61 61>
console.log(buf.fill('aazz', 'hex'));
// Prints: <Buffer aa aa aa aa aa>
console.log(buf.fill('zz', 'hex'));
// Throws an exception.
```
Returns
A reference to buf.
Parameters
- value: string | number | Uint8Array
  
  The value with which to fill buf.
- Optional offset: number
  
  Number of bytes to skip before starting to fill buf.
- Optional end: number
  
  Where to stop filling buf (not inclusive).
- Optional encoding: BufferEncoding
  
  The encoding for value if value is a string.
Returns "buffer".Buffer

Inherited from Uint8Array.fill
fill(value: string | number | Uint8Array, offset?: number, end?: number, encoding?: BufferEncoding): "buffer".Buffer
Fills buf with the specified value. If the offset and end are not given, the entire buf will be filled:
```
import { Buffer } from 'buffer';

// Fill a `Buffer` with the ASCII character 'h'.

const b = Buffer.allocUnsafe(50).fill('h');

console.log(b.toString());
// Prints: hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
```
value is coerced to a uint32 value if it is not a string, Buffer, or integer. If the resulting integer is greater than 255 (decimal), buf will be filled with value & 255.

If the final write of a fill() operation falls on a multi-byte character, then only the bytes of that character that fit into buf are written:
```
import { Buffer } from 'buffer';

// Fill a `Buffer` with character that takes up two bytes in UTF-8.

console.log(Buffer.allocUnsafe(5).fill('\u0222'));
// Prints: <Buffer c8 a2 c8 a2 c8>
```
If value contains invalid characters, it is truncated; if no valid fill data remains, an exception is thrown:
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(5);

console.log(buf.fill('a'));
// Prints: <Buffer 61 61 61 61 61>
console.log(buf.fill('aazz', 'hex'));
// Prints: <Buffer aa aa aa aa aa>
console.log(buf.fill('zz', 'hex'));
// Throws an exception.
```
Returns
A reference to buf.
Parameters
- value: string | number | Uint8Array
  
  The value with which to fill buf.
- Optional offset: number
  
  Number of bytes to skip before starting to fill buf.
- Optional end: number
  
  Where to stop filling buf (not inclusive).
- Optional encoding: BufferEncoding
  
  The encoding for value if value is a string.
Returns "buffer".Buffer

Inherited from Uint8Array.fill

includes

includes(value: string | number | "buffer".Buffer, byteOffset?: number, encoding?: BufferEncoding): boolean

Equivalent to buf.indexOf() !== -1.

import { Buffer } from 'buffer';

const buf = Buffer.from('this is a buffer');

console.log(buf.includes('this'));
// Prints: true
console.log(buf.includes('is'));
// Prints: true
console.log(buf.includes(Buffer.from('a buffer')));
// Prints: true
console.log(buf.includes(97));
// Prints: true (97 is the decimal ASCII value for 'a')
console.log(buf.includes(Buffer.from('a buffer example')));
// Prints: false
console.log(buf.includes(Buffer.from('a buffer example').slice(0, 8)));
// Prints: true
console.log(buf.includes('this', 4));
// Prints: false

Returns

true if value was found in buf, false otherwise.

Parameters

value: string | number | "buffer".Buffer

What to search for.
Optional byteOffset: number

Where to begin searching in buf. If negative, then offset is calculated from the end of buf.
Optional encoding: BufferEncoding

If value is a string, this is its encoding.

Returns boolean

includes(value: string | number | "buffer".Buffer, byteOffset?: number, encoding?: BufferEncoding): boolean

Equivalent to buf.indexOf() !== -1.

import { Buffer } from 'buffer';

const buf = Buffer.from('this is a buffer');

console.log(buf.includes('this'));
// Prints: true
console.log(buf.includes('is'));
// Prints: true
console.log(buf.includes(Buffer.from('a buffer')));
// Prints: true
console.log(buf.includes(97));
// Prints: true (97 is the decimal ASCII value for 'a')
console.log(buf.includes(Buffer.from('a buffer example')));
// Prints: false
console.log(buf.includes(Buffer.from('a buffer example').slice(0, 8)));
// Prints: true
console.log(buf.includes('this', 4));
// Prints: false

Returns

true if value was found in buf, false otherwise.

Parameters

value: string | number | "buffer".Buffer

What to search for.
Optional byteOffset: number

Where to begin searching in buf. If negative, then offset is calculated from the end of buf.
Optional encoding: BufferEncoding

If value is a string, this is its encoding.

Returns boolean

indexOf

indexOf(value: string | number | Uint8Array, byteOffset?: number, encoding?: BufferEncoding): number
If value is:
- a string, value is interpreted according to the character encoding inencoding.
- a Buffer or Uint8Array, value will be used in its entirety. To compare a partial Buffer, use buf.subarray.
- a number, value will be interpreted as an unsigned 8-bit integer value between 0 and 255.
```
import { Buffer } from 'buffer';

const buf = Buffer.from('this is a buffer');

console.log(buf.indexOf('this'));
// Prints: 0
console.log(buf.indexOf('is'));
// Prints: 2
console.log(buf.indexOf(Buffer.from('a buffer')));
// Prints: 8
console.log(buf.indexOf(97));
// Prints: 8 (97 is the decimal ASCII value for 'a')
console.log(buf.indexOf(Buffer.from('a buffer example')));
// Prints: -1
console.log(buf.indexOf(Buffer.from('a buffer example').slice(0, 8)));
// Prints: 8

const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'utf16le');

console.log(utf16Buffer.indexOf('\u03a3', 0, 'utf16le'));
// Prints: 4
console.log(utf16Buffer.indexOf('\u03a3', -4, 'utf16le'));
// Prints: 6
```
If value is not a string, number, or Buffer, this method will throw aTypeError. If value is a number, it will be coerced to a valid byte value, an integer between 0 and 255.

If byteOffset is not a number, it will be coerced to a number. If the result of coercion is NaN or 0, then the entire buffer will be searched. This behavior matches String.prototype.indexOf().
```
import { Buffer } from 'buffer';

const b = Buffer.from('abcdef');

// Passing a value that's a number, but not a valid byte.
// Prints: 2, equivalent to searching for 99 or 'c'.
console.log(b.indexOf(99.9));
console.log(b.indexOf(256 + 99));

// Passing a byteOffset that coerces to NaN or 0.
// Prints: 1, searching the whole buffer.
console.log(b.indexOf('b', undefined));
console.log(b.indexOf('b', {}));
console.log(b.indexOf('b', null));
console.log(b.indexOf('b', []));
```
If value is an empty string or empty Buffer and byteOffset is less than buf.length, byteOffset will be returned. If value is empty andbyteOffset is at least buf.length, buf.length will be returned.

Returns
The index of the first occurrence of value in buf, or -1 if buf does not contain value.
Parameters
- value: string | number | Uint8Array
  
  What to search for.
- Optional byteOffset: number
  
  Where to begin searching in buf. If negative, then offset is calculated from the end of buf.
- Optional encoding: BufferEncoding
  
  If value is a string, this is the encoding used to determine the binary representation of the string that will be searched for in buf.
Returns number

Inherited from Uint8Array.indexOf
indexOf(value: string | number | Uint8Array, byteOffset?: number, encoding?: BufferEncoding): number
If value is:
- a string, value is interpreted according to the character encoding inencoding.
- a Buffer or Uint8Array, value will be used in its entirety. To compare a partial Buffer, use buf.subarray.
- a number, value will be interpreted as an unsigned 8-bit integer value between 0 and 255.
```
import { Buffer } from 'buffer';

const buf = Buffer.from('this is a buffer');

console.log(buf.indexOf('this'));
// Prints: 0
console.log(buf.indexOf('is'));
// Prints: 2
console.log(buf.indexOf(Buffer.from('a buffer')));
// Prints: 8
console.log(buf.indexOf(97));
// Prints: 8 (97 is the decimal ASCII value for 'a')
console.log(buf.indexOf(Buffer.from('a buffer example')));
// Prints: -1
console.log(buf.indexOf(Buffer.from('a buffer example').slice(0, 8)));
// Prints: 8

const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'utf16le');

console.log(utf16Buffer.indexOf('\u03a3', 0, 'utf16le'));
// Prints: 4
console.log(utf16Buffer.indexOf('\u03a3', -4, 'utf16le'));
// Prints: 6
```
If value is not a string, number, or Buffer, this method will throw aTypeError. If value is a number, it will be coerced to a valid byte value, an integer between 0 and 255.

If byteOffset is not a number, it will be coerced to a number. If the result of coercion is NaN or 0, then the entire buffer will be searched. This behavior matches String.prototype.indexOf().
```
import { Buffer } from 'buffer';

const b = Buffer.from('abcdef');

// Passing a value that's a number, but not a valid byte.
// Prints: 2, equivalent to searching for 99 or 'c'.
console.log(b.indexOf(99.9));
console.log(b.indexOf(256 + 99));

// Passing a byteOffset that coerces to NaN or 0.
// Prints: 1, searching the whole buffer.
console.log(b.indexOf('b', undefined));
console.log(b.indexOf('b', {}));
console.log(b.indexOf('b', null));
console.log(b.indexOf('b', []));
```
If value is an empty string or empty Buffer and byteOffset is less than buf.length, byteOffset will be returned. If value is empty andbyteOffset is at least buf.length, buf.length will be returned.

Returns
The index of the first occurrence of value in buf, or -1 if buf does not contain value.
Parameters
- value: string | number | Uint8Array
  
  What to search for.
- Optional byteOffset: number
  
  Where to begin searching in buf. If negative, then offset is calculated from the end of buf.
- Optional encoding: BufferEncoding
  
  If value is a string, this is the encoding used to determine the binary representation of the string that will be searched for in buf.
Returns number

Inherited from Uint8Array.indexOf

keys

keys(): IterableIterator<number>

Creates and returns an iterator of buf keys (indices).

import { Buffer } from 'buffer';

const buf = Buffer.from('buffer');

for (const key of buf.keys()) {
  console.log(key);
}
// Prints:
//   0
//   1
//   2
//   3
//   4
//   5

Returns IterableIterator<number>

keys(): IterableIterator<number>

Creates and returns an iterator of buf keys (indices).

import { Buffer } from 'buffer';

const buf = Buffer.from('buffer');

for (const key of buf.keys()) {
  console.log(key);
}
// Prints:
//   0
//   1
//   2
//   3
//   4
//   5

Returns IterableIterator<number>

lastIndexOf

lastIndexOf(value: string | number | Uint8Array, byteOffset?: number, encoding?: BufferEncoding): number

Identical to buf.indexOf(), except the last occurrence of value is found rather than the first occurrence.

import { Buffer } from 'buffer';

const buf = Buffer.from('this buffer is a buffer');

console.log(buf.lastIndexOf('this'));
// Prints: 0
console.log(buf.lastIndexOf('buffer'));
// Prints: 17
console.log(buf.lastIndexOf(Buffer.from('buffer')));
// Prints: 17
console.log(buf.lastIndexOf(97));
// Prints: 15 (97 is the decimal ASCII value for 'a')
console.log(buf.lastIndexOf(Buffer.from('yolo')));
// Prints: -1
console.log(buf.lastIndexOf('buffer', 5));
// Prints: 5
console.log(buf.lastIndexOf('buffer', 4));
// Prints: -1

const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'utf16le');

console.log(utf16Buffer.lastIndexOf('\u03a3', undefined, 'utf16le'));
// Prints: 6
console.log(utf16Buffer.lastIndexOf('\u03a3', -5, 'utf16le'));
// Prints: 4

If value is not a string, number, or Buffer, this method will throw aTypeError. If value is a number, it will be coerced to a valid byte value, an integer between 0 and 255.

If byteOffset is not a number, it will be coerced to a number. Any arguments that coerce to NaN, like {} or undefined, will search the whole buffer. This behavior matches String.prototype.lastIndexOf().

import { Buffer } from 'buffer';

const b = Buffer.from('abcdef');

// Passing a value that's a number, but not a valid byte.
// Prints: 2, equivalent to searching for 99 or 'c'.
console.log(b.lastIndexOf(99.9));
console.log(b.lastIndexOf(256 + 99));

// Passing a byteOffset that coerces to NaN.
// Prints: 1, searching the whole buffer.
console.log(b.lastIndexOf('b', undefined));
console.log(b.lastIndexOf('b', {}));

// Passing a byteOffset that coerces to 0.
// Prints: -1, equivalent to passing 0.
console.log(b.lastIndexOf('b', null));
console.log(b.lastIndexOf('b', []));

If value is an empty string or empty Buffer, byteOffset will be returned.

Returns

The index of the last occurrence of value in buf, or -1 if buf does not contain value.

Parameters

value: string | number | Uint8Array

What to search for.
Optional byteOffset: number
Optional encoding: BufferEncoding

If value is a string, this is the encoding used to determine the binary representation of the string that will be searched for in buf.

Returns number

lastIndexOf(value: string | number | Uint8Array, byteOffset?: number, encoding?: BufferEncoding): number

Identical to buf.indexOf(), except the last occurrence of value is found rather than the first occurrence.

import { Buffer } from 'buffer';

const buf = Buffer.from('this buffer is a buffer');

console.log(buf.lastIndexOf('this'));
// Prints: 0
console.log(buf.lastIndexOf('buffer'));
// Prints: 17
console.log(buf.lastIndexOf(Buffer.from('buffer')));
// Prints: 17
console.log(buf.lastIndexOf(97));
// Prints: 15 (97 is the decimal ASCII value for 'a')
console.log(buf.lastIndexOf(Buffer.from('yolo')));
// Prints: -1
console.log(buf.lastIndexOf('buffer', 5));
// Prints: 5
console.log(buf.lastIndexOf('buffer', 4));
// Prints: -1

const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'utf16le');

console.log(utf16Buffer.lastIndexOf('\u03a3', undefined, 'utf16le'));
// Prints: 6
console.log(utf16Buffer.lastIndexOf('\u03a3', -5, 'utf16le'));
// Prints: 4

If value is not a string, number, or Buffer, this method will throw aTypeError. If value is a number, it will be coerced to a valid byte value, an integer between 0 and 255.

import { Buffer } from 'buffer';

const b = Buffer.from('abcdef');

// Passing a value that's a number, but not a valid byte.
// Prints: 2, equivalent to searching for 99 or 'c'.
console.log(b.lastIndexOf(99.9));
console.log(b.lastIndexOf(256 + 99));

// Passing a byteOffset that coerces to NaN.
// Prints: 1, searching the whole buffer.
console.log(b.lastIndexOf('b', undefined));
console.log(b.lastIndexOf('b', {}));

// Passing a byteOffset that coerces to 0.
// Prints: -1, equivalent to passing 0.
console.log(b.lastIndexOf('b', null));
console.log(b.lastIndexOf('b', []));

If value is an empty string or empty Buffer, byteOffset will be returned.

Returns

The index of the last occurrence of value in buf, or -1 if buf does not contain value.

Parameters

value: string | number | Uint8Array

What to search for.
Optional byteOffset: number
Optional encoding: BufferEncoding

If value is a string, this is the encoding used to determine the binary representation of the string that will be searched for in buf.

Returns number

readBigInt64BE

readBigInt64BE(offset?: number): bigint
Reads a signed, big-endian 64-bit integer from buf at the specified offset.

Integers read from a Buffer are interpreted as two's complement signed values.
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.
Returns bigint
readBigInt64BE(offset?: number): bigint
Reads a signed, big-endian 64-bit integer from buf at the specified offset.

Integers read from a Buffer are interpreted as two's complement signed values.
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.
Returns bigint

readBigInt64LE

readBigInt64LE(offset?: number): bigint
Reads a signed, little-endian 64-bit integer from buf at the specifiedoffset.

Integers read from a Buffer are interpreted as two's complement signed values.
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.
Returns bigint
readBigInt64LE(offset?: number): bigint
Reads a signed, little-endian 64-bit integer from buf at the specifiedoffset.

Integers read from a Buffer are interpreted as two's complement signed values.
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.
Returns bigint

readBigUInt64BE

readBigUInt64BE(offset?: number): bigint
Reads an unsigned, big-endian 64-bit integer from buf at the specifiedoffset.

This function is also available under the readBigUint64BE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff]);

console.log(buf.readBigUInt64BE(0));
// Prints: 4294967295n
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.
Returns bigint
readBigUInt64BE(offset?: number): bigint
Reads an unsigned, big-endian 64-bit integer from buf at the specifiedoffset.

This function is also available under the readBigUint64BE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff]);

console.log(buf.readBigUInt64BE(0));
// Prints: 4294967295n
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.
Returns bigint

readBigUInt64LE

readBigUInt64LE(offset?: number): bigint
Reads an unsigned, little-endian 64-bit integer from buf at the specifiedoffset.

This function is also available under the readBigUint64LE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff]);

console.log(buf.readBigUInt64LE(0));
// Prints: 18446744069414584320n
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.
Returns bigint
readBigUInt64LE(offset?: number): bigint
Reads an unsigned, little-endian 64-bit integer from buf at the specifiedoffset.

This function is also available under the readBigUint64LE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff]);

console.log(buf.readBigUInt64LE(0));
// Prints: 18446744069414584320n
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8.
Returns bigint

readBigUint64BE

readBigUint64BE(offset?: number): bigint
Alias
Buffer.readBigUInt64BE
Parameters
- Optional offset: number
Returns bigint
readBigUint64BE(offset?: number): bigint
Alias
Buffer.readBigUInt64BE
Parameters
- Optional offset: number
Returns bigint

readBigUint64LE

readBigUint64LE(offset?: number): bigint
Alias
Buffer.readBigUInt64LE
Parameters
- Optional offset: number
Returns bigint
readBigUint64LE(offset?: number): bigint
Alias
Buffer.readBigUInt64LE
Parameters
- Optional offset: number
Returns bigint

readDoubleBE

readDoubleBE(offset?: number): number
Reads a 64-bit, big-endian double from buf at the specified offset.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);

console.log(buf.readDoubleBE(0));
// Prints: 8.20788039913184e-304
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 8.
Returns number
readDoubleBE(offset?: number): number
Reads a 64-bit, big-endian double from buf at the specified offset.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);

console.log(buf.readDoubleBE(0));
// Prints: 8.20788039913184e-304
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 8.
Returns number

readDoubleLE

readDoubleLE(offset?: number): number

Reads a 64-bit, little-endian double from buf at the specified offset.

import { Buffer } from 'buffer';

const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);

console.log(buf.readDoubleLE(0));
// Prints: 5.447603722011605e-270
console.log(buf.readDoubleLE(1));
// Throws ERR_OUT_OF_RANGE.

Parameters

Optional offset: number

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 8.

Returns number

readDoubleLE(offset?: number): number

Reads a 64-bit, little-endian double from buf at the specified offset.

import { Buffer } from 'buffer';

const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);

console.log(buf.readDoubleLE(0));
// Prints: 5.447603722011605e-270
console.log(buf.readDoubleLE(1));
// Throws ERR_OUT_OF_RANGE.

Parameters

Optional offset: number

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 8.

Returns number

readFloatBE

readFloatBE(offset?: number): number
Reads a 32-bit, big-endian float from buf at the specified offset.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([1, 2, 3, 4]);

console.log(buf.readFloatBE(0));
// Prints: 2.387939260590663e-38
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Returns number
readFloatBE(offset?: number): number
Reads a 32-bit, big-endian float from buf at the specified offset.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([1, 2, 3, 4]);

console.log(buf.readFloatBE(0));
// Prints: 2.387939260590663e-38
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Returns number

readFloatLE

readFloatLE(offset?: number): number

Reads a 32-bit, little-endian float from buf at the specified offset.

import { Buffer } from 'buffer';

const buf = Buffer.from([1, 2, 3, 4]);

console.log(buf.readFloatLE(0));
// Prints: 1.539989614439558e-36
console.log(buf.readFloatLE(1));
// Throws ERR_OUT_OF_RANGE.

Parameters

Optional offset: number

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.

Returns number

readFloatLE(offset?: number): number

Reads a 32-bit, little-endian float from buf at the specified offset.

import { Buffer } from 'buffer';

const buf = Buffer.from([1, 2, 3, 4]);

console.log(buf.readFloatLE(0));
// Prints: 1.539989614439558e-36
console.log(buf.readFloatLE(1));
// Throws ERR_OUT_OF_RANGE.

Parameters

Optional offset: number

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.

Returns number

readInt16BE

readInt16BE(offset?: number): number
Reads a signed, big-endian 16-bit integer from buf at the specified offset.

Integers read from a Buffer are interpreted as two's complement signed values.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0, 5]);

console.log(buf.readInt16BE(0));
// Prints: 5
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.
Returns number
readInt16BE(offset?: number): number
Reads a signed, big-endian 16-bit integer from buf at the specified offset.

Integers read from a Buffer are interpreted as two's complement signed values.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0, 5]);

console.log(buf.readInt16BE(0));
// Prints: 5
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.
Returns number

readInt16LE

readInt16LE(offset?: number): number
Reads a signed, little-endian 16-bit integer from buf at the specifiedoffset.

Integers read from a Buffer are interpreted as two's complement signed values.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0, 5]);

console.log(buf.readInt16LE(0));
// Prints: 1280
console.log(buf.readInt16LE(1));
// Throws ERR_OUT_OF_RANGE.
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.
Returns number
readInt16LE(offset?: number): number
Reads a signed, little-endian 16-bit integer from buf at the specifiedoffset.

Integers read from a Buffer are interpreted as two's complement signed values.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0, 5]);

console.log(buf.readInt16LE(0));
// Prints: 1280
console.log(buf.readInt16LE(1));
// Throws ERR_OUT_OF_RANGE.
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.
Returns number

readInt32BE

readInt32BE(offset?: number): number
Reads a signed, big-endian 32-bit integer from buf at the specified offset.

Integers read from a Buffer are interpreted as two's complement signed values.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0, 0, 0, 5]);

console.log(buf.readInt32BE(0));
// Prints: 5
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Returns number
readInt32BE(offset?: number): number
Reads a signed, big-endian 32-bit integer from buf at the specified offset.

Integers read from a Buffer are interpreted as two's complement signed values.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0, 0, 0, 5]);

console.log(buf.readInt32BE(0));
// Prints: 5
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Returns number

readInt32LE

readInt32LE(offset?: number): number
Reads a signed, little-endian 32-bit integer from buf at the specifiedoffset.

Integers read from a Buffer are interpreted as two's complement signed values.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0, 0, 0, 5]);

console.log(buf.readInt32LE(0));
// Prints: 83886080
console.log(buf.readInt32LE(1));
// Throws ERR_OUT_OF_RANGE.
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Returns number
readInt32LE(offset?: number): number
Reads a signed, little-endian 32-bit integer from buf at the specifiedoffset.

Integers read from a Buffer are interpreted as two's complement signed values.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0, 0, 0, 5]);

console.log(buf.readInt32LE(0));
// Prints: 83886080
console.log(buf.readInt32LE(1));
// Throws ERR_OUT_OF_RANGE.
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Returns number

readInt8

readInt8(offset?: number): number
Reads a signed 8-bit integer from buf at the specified offset.

Integers read from a Buffer are interpreted as two's complement signed values.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([-1, 5]);

console.log(buf.readInt8(0));
// Prints: -1
console.log(buf.readInt8(1));
// Prints: 5
console.log(buf.readInt8(2));
// Throws ERR_OUT_OF_RANGE.
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 1.
Returns number
readInt8(offset?: number): number
Reads a signed 8-bit integer from buf at the specified offset.

Integers read from a Buffer are interpreted as two's complement signed values.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([-1, 5]);

console.log(buf.readInt8(0));
// Prints: -1
console.log(buf.readInt8(1));
// Prints: 5
console.log(buf.readInt8(2));
// Throws ERR_OUT_OF_RANGE.
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 1.
Returns number

readIntBE

readIntBE(offset: number, byteLength: number): number
Reads byteLength number of bytes from buf at the specified offsetand interprets the result as a big-endian, two's complement signed value supporting up to 48 bits of accuracy.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readIntBE(0, 6).toString(16));
// Prints: 1234567890ab
console.log(buf.readIntBE(1, 6).toString(16));
// Throws ERR_OUT_OF_RANGE.
console.log(buf.readIntBE(1, 0).toString(16));
// Throws ERR_OUT_OF_RANGE.
```
Note: as of Bun v0.1.2, this is not implemented yet.
Parameters
- offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to read. Must satisfy 0 < byteLength <= 6.
Returns number
readIntBE(offset: number, byteLength: number): number
Reads byteLength number of bytes from buf at the specified offsetand interprets the result as a big-endian, two's complement signed value supporting up to 48 bits of accuracy.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readIntBE(0, 6).toString(16));
// Prints: 1234567890ab
console.log(buf.readIntBE(1, 6).toString(16));
// Throws ERR_OUT_OF_RANGE.
console.log(buf.readIntBE(1, 0).toString(16));
// Throws ERR_OUT_OF_RANGE.
```
Note: as of Bun v0.1.2, this is not implemented yet.
Parameters
- offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to read. Must satisfy 0 < byteLength <= 6.
Returns number

readIntLE

readIntLE(offset: number, byteLength: number): number
Reads byteLength number of bytes from buf at the specified offsetand interprets the result as a little-endian, two's complement signed value supporting up to 48 bits of accuracy.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readIntLE(0, 6).toString(16));
// Prints: -546f87a9cbee
```
Note: as of Bun v0.1.2, this is not implemented yet.
Parameters
- offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to read. Must satisfy 0 < byteLength <= 6.
Returns number
readIntLE(offset: number, byteLength: number): number
Reads byteLength number of bytes from buf at the specified offsetand interprets the result as a little-endian, two's complement signed value supporting up to 48 bits of accuracy.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readIntLE(0, 6).toString(16));
// Prints: -546f87a9cbee
```
Note: as of Bun v0.1.2, this is not implemented yet.
Parameters
- offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to read. Must satisfy 0 < byteLength <= 6.
Returns number

readUInt16BE

readUInt16BE(offset?: number): number
Reads an unsigned, big-endian 16-bit integer from buf at the specifiedoffset.

This function is also available under the readUint16BE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56]);

console.log(buf.readUInt16BE(0).toString(16));
// Prints: 1234
console.log(buf.readUInt16BE(1).toString(16));
// Prints: 3456
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.
Returns number
readUInt16BE(offset?: number): number
Reads an unsigned, big-endian 16-bit integer from buf at the specifiedoffset.

This function is also available under the readUint16BE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56]);

console.log(buf.readUInt16BE(0).toString(16));
// Prints: 1234
console.log(buf.readUInt16BE(1).toString(16));
// Prints: 3456
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.
Returns number

readUInt16LE

readUInt16LE(offset?: number): number

Reads an unsigned, little-endian 16-bit integer from buf at the specifiedoffset.

This function is also available under the readUint16LE alias.

import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56]);

console.log(buf.readUInt16LE(0).toString(16));
// Prints: 3412
console.log(buf.readUInt16LE(1).toString(16));
// Prints: 5634
console.log(buf.readUInt16LE(2).toString(16));
// Throws ERR_OUT_OF_RANGE.

Parameters

Optional offset: number

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.

Returns number

readUInt16LE(offset?: number): number

Reads an unsigned, little-endian 16-bit integer from buf at the specifiedoffset.

This function is also available under the readUint16LE alias.

import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56]);

console.log(buf.readUInt16LE(0).toString(16));
// Prints: 3412
console.log(buf.readUInt16LE(1).toString(16));
// Prints: 5634
console.log(buf.readUInt16LE(2).toString(16));
// Throws ERR_OUT_OF_RANGE.

Parameters

Optional offset: number

Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2.

Returns number

readUInt32BE

readUInt32BE(offset?: number): number
Reads an unsigned, big-endian 32-bit integer from buf at the specifiedoffset.

This function is also available under the readUint32BE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);

console.log(buf.readUInt32BE(0).toString(16));
// Prints: 12345678
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Returns number
readUInt32BE(offset?: number): number
Reads an unsigned, big-endian 32-bit integer from buf at the specifiedoffset.

This function is also available under the readUint32BE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);

console.log(buf.readUInt32BE(0).toString(16));
// Prints: 12345678
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Returns number

readUInt32LE

readUInt32LE(offset?: number): number
Reads an unsigned, little-endian 32-bit integer from buf at the specifiedoffset.

This function is also available under the readUint32LE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);

console.log(buf.readUInt32LE(0).toString(16));
// Prints: 78563412
console.log(buf.readUInt32LE(1).toString(16));
// Throws ERR_OUT_OF_RANGE.
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Returns number
readUInt32LE(offset?: number): number
Reads an unsigned, little-endian 32-bit integer from buf at the specifiedoffset.

This function is also available under the readUint32LE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);

console.log(buf.readUInt32LE(0).toString(16));
// Prints: 78563412
console.log(buf.readUInt32LE(1).toString(16));
// Throws ERR_OUT_OF_RANGE.
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4.
Returns number

readUInt8

readUInt8(offset?: number): number
Reads an unsigned 8-bit integer from buf at the specified offset.

This function is also available under the readUint8 alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([1, -2]);

console.log(buf.readUInt8(0));
// Prints: 1
console.log(buf.readUInt8(1));
// Prints: 254
console.log(buf.readUInt8(2));
// Throws ERR_OUT_OF_RANGE.
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 1.
Returns number
readUInt8(offset?: number): number
Reads an unsigned 8-bit integer from buf at the specified offset.

This function is also available under the readUint8 alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([1, -2]);

console.log(buf.readUInt8(0));
// Prints: 1
console.log(buf.readUInt8(1));
// Prints: 254
console.log(buf.readUInt8(2));
// Throws ERR_OUT_OF_RANGE.
```
Parameters
- Optional offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 1.
Returns number

readUIntBE

readUIntBE(offset: number, byteLength: number): number
Reads byteLength number of bytes from buf at the specified offsetand interprets the result as an unsigned big-endian integer supporting up to 48 bits of accuracy.

This function is also available under the readUintBE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readUIntBE(0, 6).toString(16));
// Prints: 1234567890ab
console.log(buf.readUIntBE(1, 6).toString(16));
// Throws ERR_OUT_OF_RANGE.
```
Note: as of Bun v0.1.2, this is not implemented yet.
Parameters
- offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to read. Must satisfy 0 < byteLength <= 6.
Returns number
readUIntBE(offset: number, byteLength: number): number
Reads byteLength number of bytes from buf at the specified offsetand interprets the result as an unsigned big-endian integer supporting up to 48 bits of accuracy.

This function is also available under the readUintBE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readUIntBE(0, 6).toString(16));
// Prints: 1234567890ab
console.log(buf.readUIntBE(1, 6).toString(16));
// Throws ERR_OUT_OF_RANGE.
```
Note: as of Bun v0.1.2, this is not implemented yet.
Parameters
- offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to read. Must satisfy 0 < byteLength <= 6.
Returns number

readUIntLE

readUIntLE(offset: number, byteLength: number): number
Reads byteLength number of bytes from buf at the specified offsetand interprets the result as an unsigned, little-endian integer supporting up to 48 bits of accuracy.

This function is also available under the readUintLE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readUIntLE(0, 6).toString(16));
// Prints: ab9078563412
```
Note: as of Bun v0.1.2, this is not implemented yet.
Parameters
- offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to read. Must satisfy 0 < byteLength <= 6.
Returns number
readUIntLE(offset: number, byteLength: number): number
Reads byteLength number of bytes from buf at the specified offsetand interprets the result as an unsigned, little-endian integer supporting up to 48 bits of accuracy.

This function is also available under the readUintLE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readUIntLE(0, 6).toString(16));
// Prints: ab9078563412
```
Note: as of Bun v0.1.2, this is not implemented yet.
Parameters
- offset: number
  
  Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to read. Must satisfy 0 < byteLength <= 6.
Returns number

readUint16BE

readUint16BE(offset?: number): number
Alias
Buffer.readUInt16BE
Parameters
- Optional offset: number
Returns number
readUint16BE(offset?: number): number
Alias
Buffer.readUInt16BE
Parameters
- Optional offset: number
Returns number

readUint16LE

readUint16LE(offset?: number): number
Alias
Buffer.readUInt16LE
Parameters
- Optional offset: number
Returns number
readUint16LE(offset?: number): number
Alias
Buffer.readUInt16LE
Parameters
- Optional offset: number
Returns number

readUint32BE

readUint32BE(offset?: number): number
Alias
Buffer.readUInt32BE
Parameters
- Optional offset: number
Returns number
readUint32BE(offset?: number): number
Alias
Buffer.readUInt32BE
Parameters
- Optional offset: number
Returns number

readUint32LE

readUint32LE(offset?: number): number
Alias
Buffer.readUInt32LE
Parameters
- Optional offset: number
Returns number
readUint32LE(offset?: number): number
Alias
Buffer.readUInt32LE
Parameters
- Optional offset: number
Returns number

readUint8

readUint8(offset?: number): number
Alias
Buffer.readUInt8
Parameters
- Optional offset: number
Returns number
readUint8(offset?: number): number
Alias
Buffer.readUInt8
Parameters
- Optional offset: number
Returns number

readUintBE

readUintBE(offset: number, byteLength: number): number
Alias
Buffer.readUIntBE
Parameters
- offset: number
- byteLength: number
Returns number
readUintBE(offset: number, byteLength: number): number
Alias
Buffer.readUIntBE
Parameters
- offset: number
- byteLength: number
Returns number

readUintLE

readUintLE(offset: number, byteLength: number): number
Alias
Buffer.readUIntLE
Parameters
- offset: number
- byteLength: number
Returns number
readUintLE(offset: number, byteLength: number): number
Alias
Buffer.readUIntLE
Parameters
- offset: number
- byteLength: number
Returns number

reverse

reverse(): "buffer".Buffer
Returns "buffer".Buffer

Inherited from Uint8Array.reverse
reverse(): "buffer".Buffer
Returns "buffer".Buffer

Inherited from Uint8Array.reverse

slice

slice(start?: number, end?: number): "buffer".Buffer

Returns a new Buffer that references the same memory as the original, but offset and cropped by the start and end indices.

This method is not compatible with the Uint8Array.prototype.slice(), which is a superclass of Buffer. To copy the slice, useUint8Array.prototype.slice().

import { Buffer } from 'buffer';

const buf = Buffer.from('buffer');

const copiedBuf = Uint8Array.prototype.slice.call(buf);
copiedBuf[0]++;
console.log(copiedBuf.toString());
// Prints: cuffer

console.log(buf.toString());
// Prints: buffer

// With buf.slice(), the original buffer is modified.
const notReallyCopiedBuf = buf.slice();
notReallyCopiedBuf[0]++;
console.log(notReallyCopiedBuf.toString());
// Prints: cuffer
console.log(buf.toString());
// Also prints: cuffer (!)

Deprecated

Use subarray instead.

Parameters

Optional start: number

Where the new Buffer will start.
Optional end: number

Where the new Buffer will end (not inclusive).

Returns "buffer".Buffer

slice(start?: number, end?: number): "buffer".Buffer

Returns a new Buffer that references the same memory as the original, but offset and cropped by the start and end indices.

This method is not compatible with the Uint8Array.prototype.slice(), which is a superclass of Buffer. To copy the slice, useUint8Array.prototype.slice().

import { Buffer } from 'buffer';

const buf = Buffer.from('buffer');

const copiedBuf = Uint8Array.prototype.slice.call(buf);
copiedBuf[0]++;
console.log(copiedBuf.toString());
// Prints: cuffer

console.log(buf.toString());
// Prints: buffer

// With buf.slice(), the original buffer is modified.
const notReallyCopiedBuf = buf.slice();
notReallyCopiedBuf[0]++;
console.log(notReallyCopiedBuf.toString());
// Prints: cuffer
console.log(buf.toString());
// Also prints: cuffer (!)

Deprecated

Use subarray instead.

Parameters

Optional start: number

Where the new Buffer will start.
Optional end: number

Where the new Buffer will end (not inclusive).

Returns "buffer".Buffer

subarray

subarray(start?: number, end?: number): "buffer".Buffer

Returns a new Buffer that references the same memory as the original, but offset and cropped by the start and end indices.

Specifying end greater than buf.length will return the same result as that of end equal to buf.length.

This method is inherited from TypedArray.prototype.subarray().

Modifying the new Buffer slice will modify the memory in the original Bufferbecause the allocated memory of the two objects overlap.

import { Buffer } from 'buffer';

// Create a `Buffer` with the ASCII alphabet, take a slice, and modify one byte
// from the original `Buffer`.

const buf1 = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

const buf2 = buf1.subarray(0, 3);

console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: abc

buf1[0] = 33;

console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: !bc

Specifying negative indexes causes the slice to be generated relative to the end of buf rather than the beginning.

import { Buffer } from 'buffer';

const buf = Buffer.from('buffer');

console.log(buf.subarray(-6, -1).toString());
// Prints: buffe
// (Equivalent to buf.subarray(0, 5).)

console.log(buf.subarray(-6, -2).toString());
// Prints: buff
// (Equivalent to buf.subarray(0, 4).)

console.log(buf.subarray(-5, -2).toString());
// Prints: uff
// (Equivalent to buf.subarray(1, 4).)

Parameters

Optional start: number

Where the new Buffer will start.
Optional end: number

Where the new Buffer will end (not inclusive).

Returns "buffer".Buffer

subarray(start?: number, end?: number): "buffer".Buffer

Returns a new Buffer that references the same memory as the original, but offset and cropped by the start and end indices.

Specifying end greater than buf.length will return the same result as that of end equal to buf.length.

This method is inherited from TypedArray.prototype.subarray().

Modifying the new Buffer slice will modify the memory in the original Bufferbecause the allocated memory of the two objects overlap.

import { Buffer } from 'buffer';

// Create a `Buffer` with the ASCII alphabet, take a slice, and modify one byte
// from the original `Buffer`.

const buf1 = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

const buf2 = buf1.subarray(0, 3);

console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: abc

buf1[0] = 33;

console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: !bc

Specifying negative indexes causes the slice to be generated relative to the end of buf rather than the beginning.

import { Buffer } from 'buffer';

const buf = Buffer.from('buffer');

console.log(buf.subarray(-6, -1).toString());
// Prints: buffe
// (Equivalent to buf.subarray(0, 5).)

console.log(buf.subarray(-6, -2).toString());
// Prints: buff
// (Equivalent to buf.subarray(0, 4).)

console.log(buf.subarray(-5, -2).toString());
// Prints: uff
// (Equivalent to buf.subarray(1, 4).)

Parameters

Optional start: number

Where the new Buffer will start.
Optional end: number

Where the new Buffer will end (not inclusive).

Returns "buffer".Buffer

swap16

swap16(): "buffer".Buffer

Interprets buf as an array of unsigned 16-bit integers and swaps the byte order in-place. Throws ERR_INVALID_BUFFER_SIZE if buf.length is not a multiple of 2.

import { Buffer } from 'buffer';

const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);

console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>

buf1.swap16();

console.log(buf1);
// Prints: <Buffer 02 01 04 03 06 05 08 07>

const buf2 = Buffer.from([0x1, 0x2, 0x3]);

buf2.swap16();
// Throws ERR_INVALID_BUFFER_SIZE.

One convenient use of buf.swap16() is to perform a fast in-place conversion between UTF-16 little-endian and UTF-16 big-endian:

import { Buffer } from 'buffer';

const buf = Buffer.from('This is little-endian UTF-16', 'utf16le');
buf.swap16(); // Convert to big-endian UTF-16 text.

Returns

A reference to buf.

Returns "buffer".Buffer

swap16(): "buffer".Buffer

Interprets buf as an array of unsigned 16-bit integers and swaps the byte order in-place. Throws ERR_INVALID_BUFFER_SIZE if buf.length is not a multiple of 2.

import { Buffer } from 'buffer';

const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);

console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>

buf1.swap16();

console.log(buf1);
// Prints: <Buffer 02 01 04 03 06 05 08 07>

const buf2 = Buffer.from([0x1, 0x2, 0x3]);

buf2.swap16();
// Throws ERR_INVALID_BUFFER_SIZE.

One convenient use of buf.swap16() is to perform a fast in-place conversion between UTF-16 little-endian and UTF-16 big-endian:

import { Buffer } from 'buffer';

const buf = Buffer.from('This is little-endian UTF-16', 'utf16le');
buf.swap16(); // Convert to big-endian UTF-16 text.

Returns

A reference to buf.

Returns "buffer".Buffer

swap32

swap32(): "buffer".Buffer

Interprets buf as an array of unsigned 32-bit integers and swaps the byte order in-place. Throws ERR_INVALID_BUFFER_SIZE if buf.length is not a multiple of 4.

import { Buffer } from 'buffer';

const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);

console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>

buf1.swap32();

console.log(buf1);
// Prints: <Buffer 04 03 02 01 08 07 06 05>

const buf2 = Buffer.from([0x1, 0x2, 0x3]);

buf2.swap32();
// Throws ERR_INVALID_BUFFER_SIZE.

Returns

A reference to buf.

Returns "buffer".Buffer

swap32(): "buffer".Buffer

Interprets buf as an array of unsigned 32-bit integers and swaps the byte order in-place. Throws ERR_INVALID_BUFFER_SIZE if buf.length is not a multiple of 4.

import { Buffer } from 'buffer';

const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);

console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>

buf1.swap32();

console.log(buf1);
// Prints: <Buffer 04 03 02 01 08 07 06 05>

const buf2 = Buffer.from([0x1, 0x2, 0x3]);

buf2.swap32();
// Throws ERR_INVALID_BUFFER_SIZE.

Returns

A reference to buf.

Returns "buffer".Buffer

swap64

swap64(): "buffer".Buffer

Interprets buf as an array of 64-bit numbers and swaps byte order in-place. Throws ERR_INVALID_BUFFER_SIZE if buf.length is not a multiple of 8.

import { Buffer } from 'buffer';

const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);

console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>

buf1.swap64();

console.log(buf1);
// Prints: <Buffer 08 07 06 05 04 03 02 01>

const buf2 = Buffer.from([0x1, 0x2, 0x3]);

buf2.swap64();
// Throws ERR_INVALID_BUFFER_SIZE.

Returns

A reference to buf.

Returns "buffer".Buffer

swap64(): "buffer".Buffer

Interprets buf as an array of 64-bit numbers and swaps byte order in-place. Throws ERR_INVALID_BUFFER_SIZE if buf.length is not a multiple of 8.

import { Buffer } from 'buffer';

const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);

console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>

buf1.swap64();

console.log(buf1);
// Prints: <Buffer 08 07 06 05 04 03 02 01>

const buf2 = Buffer.from([0x1, 0x2, 0x3]);

buf2.swap64();
// Throws ERR_INVALID_BUFFER_SIZE.

Returns

A reference to buf.

Returns "buffer".Buffer

toJSON

toJSON(): { data: number[]; type: "Buffer" }

Returns a JSON representation of buf. JSON.stringify() implicitly calls this function when stringifying a Buffer instance.

Buffer.from() accepts objects in the format returned from this method. In particular, Buffer.from(buf.toJSON()) works like Buffer.from(buf).

import { Buffer } from 'buffer';

const buf = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5]);
const json = JSON.stringify(buf);

console.log(json);
// Prints: {"type":"Buffer","data":[1,2,3,4,5]}

const copy = JSON.parse(json, (key, value) => {
  return value &#x26;&#x26; value.type === 'Buffer' ?
    Buffer.from(value) :
    value;
});

console.log(copy);
// Prints: <Buffer 01 02 03 04 05>

Note: as of Bun v0.1.2, this is not implemented yet.

Returns { data: number[]; type: "Buffer" }

data: number[]
type: "Buffer"

toJSON(): { data: number[]; type: "Buffer" }

Returns a JSON representation of buf. JSON.stringify() implicitly calls this function when stringifying a Buffer instance.

Buffer.from() accepts objects in the format returned from this method. In particular, Buffer.from(buf.toJSON()) works like Buffer.from(buf).

import { Buffer } from 'buffer';

const buf = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5]);
const json = JSON.stringify(buf);

console.log(json);
// Prints: {"type":"Buffer","data":[1,2,3,4,5]}

const copy = JSON.parse(json, (key, value) => {
  return value &#x26;&#x26; value.type === 'Buffer' ?
    Buffer.from(value) :
    value;
});

console.log(copy);
// Prints: <Buffer 01 02 03 04 05>

Note: as of Bun v0.1.2, this is not implemented yet.

Returns { data: number[]; type: "Buffer" }

data: number[]
type: "Buffer"

toString

toString(encoding?: BufferEncoding, start?: number, end?: number): string
Decodes buf to a string according to the specified character encoding inencoding. start and end may be passed to decode only a subset of buf.

If encoding is 'utf8' and a byte sequence in the input is not valid UTF-8, then each invalid byte is replaced with the replacement character U+FFFD.

The maximum length of a string instance (in UTF-16 code units) is available as constants.MAX_STRING_LENGTH.
```
import { Buffer } from 'buffer';

const buf1 = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

console.log(buf1.toString('utf8'));
// Prints: abcdefghijklmnopqrstuvwxyz
console.log(buf1.toString('utf8', 0, 5));
// Prints: abcde

const buf2 = Buffer.from('tést');

console.log(buf2.toString('hex'));
// Prints: 74c3a97374
console.log(buf2.toString('utf8', 0, 3));
// Prints: té
console.log(buf2.toString(undefined, 0, 3));
// Prints: té
```
Parameters
- Optional encoding: BufferEncoding
  
  The character encoding to use.
- Optional start: number
  
  The byte offset to start decoding at.
- Optional end: number
  
  The byte offset to stop decoding at (not inclusive).
Returns string

Inherited from Uint8Array.toString
toString(encoding?: BufferEncoding, start?: number, end?: number): string
Decodes buf to a string according to the specified character encoding inencoding. start and end may be passed to decode only a subset of buf.

If encoding is 'utf8' and a byte sequence in the input is not valid UTF-8, then each invalid byte is replaced with the replacement character U+FFFD.

The maximum length of a string instance (in UTF-16 code units) is available as constants.MAX_STRING_LENGTH.
```
import { Buffer } from 'buffer';

const buf1 = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

console.log(buf1.toString('utf8'));
// Prints: abcdefghijklmnopqrstuvwxyz
console.log(buf1.toString('utf8', 0, 5));
// Prints: abcde

const buf2 = Buffer.from('tést');

console.log(buf2.toString('hex'));
// Prints: 74c3a97374
console.log(buf2.toString('utf8', 0, 3));
// Prints: té
console.log(buf2.toString(undefined, 0, 3));
// Prints: té
```
Parameters
- Optional encoding: BufferEncoding
  
  The character encoding to use.
- Optional start: number
  
  The byte offset to start decoding at.
- Optional end: number
  
  The byte offset to stop decoding at (not inclusive).
Returns string

Inherited from Uint8Array.toString

values

values(): IterableIterator<number>

Creates and returns an iterator for buf values (bytes). This function is called automatically when a Buffer is used in a for..of statement.

import { Buffer } from 'buffer';

const buf = Buffer.from('buffer');

for (const value of buf.values()) {
  console.log(value);
}
// Prints:
//   98
//   117
//   102
//   102
//   101
//   114

for (const value of buf) {
  console.log(value);
}
// Prints:
//   98
//   117
//   102
//   102
//   101
//   114

Returns IterableIterator<number>

values(): IterableIterator<number>

Creates and returns an iterator for buf values (bytes). This function is called automatically when a Buffer is used in a for..of statement.

import { Buffer } from 'buffer';

const buf = Buffer.from('buffer');

for (const value of buf.values()) {
  console.log(value);
}
// Prints:
//   98
//   117
//   102
//   102
//   101
//   114

for (const value of buf) {
  console.log(value);
}
// Prints:
//   98
//   117
//   102
//   102
//   101
//   114

Returns IterableIterator<number>

write

write(string: string, encoding?: BufferEncoding): number
Writes string to buf at offset according to the character encoding inencoding. The length parameter is the number of bytes to write. If buf did not contain enough space to fit the entire string, only part of string will be written. However, partially encoded characters will not be written.
```
import { Buffer } from 'buffer';

const buf = Buffer.alloc(256);

const len = buf.write('\u00bd + \u00bc = \u00be', 0);

console.log(`${len} bytes: ${buf.toString('utf8', 0, len)}`);
// Prints: 12 bytes: ½ + ¼ = ¾

const buffer = Buffer.alloc(10);

const length = buffer.write('abcd', 8);

console.log(`${length} bytes: ${buffer.toString('utf8', 8, 10)}`);
// Prints: 2 bytes : ab
```
Returns
Number of bytes written.
Parameters
- string: string
  
  String to write to buf.
- Optional encoding: BufferEncoding
  
  The character encoding of string.
Returns number
write(string: string, offset: number, encoding?: BufferEncoding): number
Parameters
- string: string
- offset: number
- Optional encoding: BufferEncoding
Returns number
write(string: string, offset: number, length: number, encoding?: BufferEncoding): number
Parameters
- string: string
- offset: number
- length: number
- Optional encoding: BufferEncoding
Returns number
write(string: string, encoding?: BufferEncoding): number
Writes string to buf at offset according to the character encoding inencoding. The length parameter is the number of bytes to write. If buf did not contain enough space to fit the entire string, only part of string will be written. However, partially encoded characters will not be written.
```
import { Buffer } from 'buffer';

const buf = Buffer.alloc(256);

const len = buf.write('\u00bd + \u00bc = \u00be', 0);

console.log(`${len} bytes: ${buf.toString('utf8', 0, len)}`);
// Prints: 12 bytes: ½ + ¼ = ¾

const buffer = Buffer.alloc(10);

const length = buffer.write('abcd', 8);

console.log(`${length} bytes: ${buffer.toString('utf8', 8, 10)}`);
// Prints: 2 bytes : ab
```
Returns
Number of bytes written.
Parameters
- string: string
  
  String to write to buf.
- Optional encoding: BufferEncoding
  
  The character encoding of string.
Returns number
write(string: string, offset: number, encoding?: BufferEncoding): number
Parameters
- string: string
- offset: number
- Optional encoding: BufferEncoding
Returns number
write(string: string, offset: number, length: number, encoding?: BufferEncoding): number
Parameters
- string: string
- offset: number
- length: number
- Optional encoding: BufferEncoding
Returns number

writeBigInt64BE

writeBigInt64BE(value: bigint, offset?: number): number
Writes value to buf at the specified offset as big-endian.

value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeBigInt64BE(0x0102030405060708n, 0);

console.log(buf);
// Prints: <Buffer 01 02 03 04 05 06 07 08>
```
Returns
offset plus the number of bytes written.
Parameters
- value: bigint
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.
Returns number
writeBigInt64BE(value: bigint, offset?: number): number
Writes value to buf at the specified offset as big-endian.

value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeBigInt64BE(0x0102030405060708n, 0);

console.log(buf);
// Prints: <Buffer 01 02 03 04 05 06 07 08>
```
Returns
offset plus the number of bytes written.
Parameters
- value: bigint
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.
Returns number

writeBigInt64LE

writeBigInt64LE(value: bigint, offset?: number): number
Writes value to buf at the specified offset as little-endian.

value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeBigInt64LE(0x0102030405060708n, 0);

console.log(buf);
// Prints: <Buffer 08 07 06 05 04 03 02 01>
```
Returns
offset plus the number of bytes written.
Parameters
- value: bigint
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.
Returns number
writeBigInt64LE(value: bigint, offset?: number): number
Writes value to buf at the specified offset as little-endian.

value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeBigInt64LE(0x0102030405060708n, 0);

console.log(buf);
// Prints: <Buffer 08 07 06 05 04 03 02 01>
```
Returns
offset plus the number of bytes written.
Parameters
- value: bigint
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.
Returns number

writeBigUInt64BE

writeBigUInt64BE(value: bigint, offset?: number): number
Writes value to buf at the specified offset as big-endian.

This function is also available under the writeBigUint64BE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeBigUInt64BE(0xdecafafecacefaden, 0);

console.log(buf);
// Prints: <Buffer de ca fa fe ca ce fa de>
```
Returns
offset plus the number of bytes written.
Parameters
- value: bigint
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.
Returns number
writeBigUInt64BE(value: bigint, offset?: number): number
Writes value to buf at the specified offset as big-endian.

This function is also available under the writeBigUint64BE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeBigUInt64BE(0xdecafafecacefaden, 0);

console.log(buf);
// Prints: <Buffer de ca fa fe ca ce fa de>
```
Returns
offset plus the number of bytes written.
Parameters
- value: bigint
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.
Returns number

writeBigUInt64LE

writeBigUInt64LE(value: bigint, offset?: number): number
Writes value to buf at the specified offset as little-endian
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeBigUInt64LE(0xdecafafecacefaden, 0);

console.log(buf);
// Prints: <Buffer de fa ce ca fe fa ca de>
```
This function is also available under the writeBigUint64LE alias.

Returns
offset plus the number of bytes written.
Parameters
- value: bigint
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.
Returns number
writeBigUInt64LE(value: bigint, offset?: number): number
Writes value to buf at the specified offset as little-endian
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeBigUInt64LE(0xdecafafecacefaden, 0);

console.log(buf);
// Prints: <Buffer de fa ce ca fe fa ca de>
```
This function is also available under the writeBigUint64LE alias.

Returns
offset plus the number of bytes written.
Parameters
- value: bigint
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8.
Returns number

writeBigUint64BE

writeBigUint64BE(value: bigint, offset?: number): number
Alias
Buffer.writeBigUInt64BE
Parameters
- value: bigint
- Optional offset: number
Returns number
writeBigUint64BE(value: bigint, offset?: number): number
Alias
Buffer.writeBigUInt64BE
Parameters
- value: bigint
- Optional offset: number
Returns number

writeBigUint64LE

writeBigUint64LE(value: bigint, offset?: number): number
Alias
Buffer.writeBigUInt64LE
Parameters
- value: bigint
- Optional offset: number
Returns number
writeBigUint64LE(value: bigint, offset?: number): number
Alias
Buffer.writeBigUInt64LE
Parameters
- value: bigint
- Optional offset: number
Returns number

writeDoubleBE

writeDoubleBE(value: number, offset?: number): number
Writes value to buf at the specified offset as big-endian. The valuemust be a JavaScript number. Behavior is undefined when value is anything other than a JavaScript number.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeDoubleBE(123.456, 0);

console.log(buf);
// Prints: <Buffer 40 5e dd 2f 1a 9f be 77>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 8.
Returns number
writeDoubleBE(value: number, offset?: number): number
Writes value to buf at the specified offset as big-endian. The valuemust be a JavaScript number. Behavior is undefined when value is anything other than a JavaScript number.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeDoubleBE(123.456, 0);

console.log(buf);
// Prints: <Buffer 40 5e dd 2f 1a 9f be 77>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 8.
Returns number

writeDoubleLE

writeDoubleLE(value: number, offset?: number): number
Writes value to buf at the specified offset as little-endian. The valuemust be a JavaScript number. Behavior is undefined when value is anything other than a JavaScript number.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeDoubleLE(123.456, 0);

console.log(buf);
// Prints: <Buffer 77 be 9f 1a 2f dd 5e 40>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 8.
Returns number
writeDoubleLE(value: number, offset?: number): number
Writes value to buf at the specified offset as little-endian. The valuemust be a JavaScript number. Behavior is undefined when value is anything other than a JavaScript number.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeDoubleLE(123.456, 0);

console.log(buf);
// Prints: <Buffer 77 be 9f 1a 2f dd 5e 40>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 8.
Returns number

writeFloatBE

writeFloatBE(value: number, offset?: number): number
Writes value to buf at the specified offset as big-endian. Behavior is undefined when value is anything other than a JavaScript number.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeFloatBE(0xcafebabe, 0);

console.log(buf);
// Prints: <Buffer 4f 4a fe bb>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
Returns number
writeFloatBE(value: number, offset?: number): number
Writes value to buf at the specified offset as big-endian. Behavior is undefined when value is anything other than a JavaScript number.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeFloatBE(0xcafebabe, 0);

console.log(buf);
// Prints: <Buffer 4f 4a fe bb>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
Returns number

writeFloatLE

writeFloatLE(value: number, offset?: number): number
Writes value to buf at the specified offset as little-endian. Behavior is undefined when value is anything other than a JavaScript number.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeFloatLE(0xcafebabe, 0);

console.log(buf);
// Prints: <Buffer bb fe 4a 4f>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
Returns number
writeFloatLE(value: number, offset?: number): number
Writes value to buf at the specified offset as little-endian. Behavior is undefined when value is anything other than a JavaScript number.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeFloatLE(0xcafebabe, 0);

console.log(buf);
// Prints: <Buffer bb fe 4a 4f>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
Returns number

writeInt16BE

writeInt16BE(value: number, offset?: number): number
Writes value to buf at the specified offset as big-endian. The valuemust be a valid signed 16-bit integer. Behavior is undefined when value is anything other than a signed 16-bit integer.

The value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(2);

buf.writeInt16BE(0x0102, 0);

console.log(buf);
// Prints: <Buffer 01 02>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.
Returns number
writeInt16BE(value: number, offset?: number): number
Writes value to buf at the specified offset as big-endian. The valuemust be a valid signed 16-bit integer. Behavior is undefined when value is anything other than a signed 16-bit integer.

The value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(2);

buf.writeInt16BE(0x0102, 0);

console.log(buf);
// Prints: <Buffer 01 02>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.
Returns number

writeInt16LE

writeInt16LE(value: number, offset?: number): number
Writes value to buf at the specified offset as little-endian. The valuemust be a valid signed 16-bit integer. Behavior is undefined when value is anything other than a signed 16-bit integer.

The value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(2);

buf.writeInt16LE(0x0304, 0);

console.log(buf);
// Prints: <Buffer 04 03>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.
Returns number
writeInt16LE(value: number, offset?: number): number
Writes value to buf at the specified offset as little-endian. The valuemust be a valid signed 16-bit integer. Behavior is undefined when value is anything other than a signed 16-bit integer.

The value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(2);

buf.writeInt16LE(0x0304, 0);

console.log(buf);
// Prints: <Buffer 04 03>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.
Returns number

writeInt32BE

writeInt32BE(value: number, offset?: number): number
Writes value to buf at the specified offset as big-endian. The valuemust be a valid signed 32-bit integer. Behavior is undefined when value is anything other than a signed 32-bit integer.

The value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeInt32BE(0x01020304, 0);

console.log(buf);
// Prints: <Buffer 01 02 03 04>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
Returns number
writeInt32BE(value: number, offset?: number): number
Writes value to buf at the specified offset as big-endian. The valuemust be a valid signed 32-bit integer. Behavior is undefined when value is anything other than a signed 32-bit integer.

The value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeInt32BE(0x01020304, 0);

console.log(buf);
// Prints: <Buffer 01 02 03 04>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
Returns number

writeInt32LE

writeInt32LE(value: number, offset?: number): number
Writes value to buf at the specified offset as little-endian. The valuemust be a valid signed 32-bit integer. Behavior is undefined when value is anything other than a signed 32-bit integer.

The value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeInt32LE(0x05060708, 0);

console.log(buf);
// Prints: <Buffer 08 07 06 05>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
Returns number
writeInt32LE(value: number, offset?: number): number
Writes value to buf at the specified offset as little-endian. The valuemust be a valid signed 32-bit integer. Behavior is undefined when value is anything other than a signed 32-bit integer.

The value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeInt32LE(0x05060708, 0);

console.log(buf);
// Prints: <Buffer 08 07 06 05>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
Returns number

writeInt8

writeInt8(value: number, offset?: number): number
Writes value to buf at the specified offset. value must be a valid signed 8-bit integer. Behavior is undefined when value is anything other than a signed 8-bit integer.

value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(2);

buf.writeInt8(2, 0);
buf.writeInt8(-2, 1);

console.log(buf);
// Prints: <Buffer 02 fe>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 1.
Returns number
writeInt8(value: number, offset?: number): number
Writes value to buf at the specified offset. value must be a valid signed 8-bit integer. Behavior is undefined when value is anything other than a signed 8-bit integer.

value is interpreted and written as a two's complement signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(2);

buf.writeInt8(2, 0);
buf.writeInt8(-2, 1);

console.log(buf);
// Prints: <Buffer 02 fe>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 1.
Returns number

writeIntBE

writeIntBE(value: number, offset: number, byteLength: number): number
Writes byteLength bytes of value to buf at the specified offsetas big-endian. Supports up to 48 bits of accuracy. Behavior is undefined whenvalue is anything other than a signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(6);

buf.writeIntBE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer 12 34 56 78 90 ab>
```
Note: as of Bun v0.1.2, this is not implemented yet.

Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to write. Must satisfy 0 < byteLength <= 6.
Returns number
writeIntBE(value: number, offset: number, byteLength: number): number
Writes byteLength bytes of value to buf at the specified offsetas big-endian. Supports up to 48 bits of accuracy. Behavior is undefined whenvalue is anything other than a signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(6);

buf.writeIntBE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer 12 34 56 78 90 ab>
```
Note: as of Bun v0.1.2, this is not implemented yet.

Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to write. Must satisfy 0 < byteLength <= 6.
Returns number

writeIntLE

writeIntLE(value: number, offset: number, byteLength: number): number
Writes byteLength bytes of value to buf at the specified offsetas little-endian. Supports up to 48 bits of accuracy. Behavior is undefined when value is anything other than a signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(6);

buf.writeIntLE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer ab 90 78 56 34 12>
```
Note: as of Bun v0.1.2, this is not implemented yet.

Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to write. Must satisfy 0 < byteLength <= 6.
Returns number
writeIntLE(value: number, offset: number, byteLength: number): number
Writes byteLength bytes of value to buf at the specified offsetas little-endian. Supports up to 48 bits of accuracy. Behavior is undefined when value is anything other than a signed integer.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(6);

buf.writeIntLE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer ab 90 78 56 34 12>
```
Note: as of Bun v0.1.2, this is not implemented yet.

Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to write. Must satisfy 0 < byteLength <= 6.
Returns number

writeUInt16BE

writeUInt16BE(value: number, offset?: number): number
Writes value to buf at the specified offset as big-endian. The valuemust be a valid unsigned 16-bit integer. Behavior is undefined when valueis anything other than an unsigned 16-bit integer.

This function is also available under the writeUint16BE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt16BE(0xdead, 0);
buf.writeUInt16BE(0xbeef, 2);

console.log(buf);
// Prints: <Buffer de ad be ef>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.
Returns number
writeUInt16BE(value: number, offset?: number): number
Writes value to buf at the specified offset as big-endian. The valuemust be a valid unsigned 16-bit integer. Behavior is undefined when valueis anything other than an unsigned 16-bit integer.

This function is also available under the writeUint16BE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt16BE(0xdead, 0);
buf.writeUInt16BE(0xbeef, 2);

console.log(buf);
// Prints: <Buffer de ad be ef>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.
Returns number

writeUInt16LE

writeUInt16LE(value: number, offset?: number): number
Writes value to buf at the specified offset as little-endian. The valuemust be a valid unsigned 16-bit integer. Behavior is undefined when value is anything other than an unsigned 16-bit integer.

This function is also available under the writeUint16LE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt16LE(0xdead, 0);
buf.writeUInt16LE(0xbeef, 2);

console.log(buf);
// Prints: <Buffer ad de ef be>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.
Returns number
writeUInt16LE(value: number, offset?: number): number
Writes value to buf at the specified offset as little-endian. The valuemust be a valid unsigned 16-bit integer. Behavior is undefined when value is anything other than an unsigned 16-bit integer.

This function is also available under the writeUint16LE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt16LE(0xdead, 0);
buf.writeUInt16LE(0xbeef, 2);

console.log(buf);
// Prints: <Buffer ad de ef be>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2.
Returns number

writeUInt32BE

writeUInt32BE(value: number, offset?: number): number
Writes value to buf at the specified offset as big-endian. The valuemust be a valid unsigned 32-bit integer. Behavior is undefined when valueis anything other than an unsigned 32-bit integer.

This function is also available under the writeUint32BE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt32BE(0xfeedface, 0);

console.log(buf);
// Prints: <Buffer fe ed fa ce>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
Returns number
writeUInt32BE(value: number, offset?: number): number
Writes value to buf at the specified offset as big-endian. The valuemust be a valid unsigned 32-bit integer. Behavior is undefined when valueis anything other than an unsigned 32-bit integer.

This function is also available under the writeUint32BE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt32BE(0xfeedface, 0);

console.log(buf);
// Prints: <Buffer fe ed fa ce>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
Returns number

writeUInt32LE

writeUInt32LE(value: number, offset?: number): number
Writes value to buf at the specified offset as little-endian. The valuemust be a valid unsigned 32-bit integer. Behavior is undefined when value is anything other than an unsigned 32-bit integer.

This function is also available under the writeUint32LE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt32LE(0xfeedface, 0);

console.log(buf);
// Prints: <Buffer ce fa ed fe>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
Returns number
writeUInt32LE(value: number, offset?: number): number
Writes value to buf at the specified offset as little-endian. The valuemust be a valid unsigned 32-bit integer. Behavior is undefined when value is anything other than an unsigned 32-bit integer.

This function is also available under the writeUint32LE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt32LE(0xfeedface, 0);

console.log(buf);
// Prints: <Buffer ce fa ed fe>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4.
Returns number

writeUInt8

writeUInt8(value: number, offset?: number): number
Writes value to buf at the specified offset. value must be a valid unsigned 8-bit integer. Behavior is undefined when value is anything other than an unsigned 8-bit integer.

This function is also available under the writeUint8 alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt8(0x3, 0);
buf.writeUInt8(0x4, 1);
buf.writeUInt8(0x23, 2);
buf.writeUInt8(0x42, 3);

console.log(buf);
// Prints: <Buffer 03 04 23 42>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 1.
Returns number
writeUInt8(value: number, offset?: number): number
Writes value to buf at the specified offset. value must be a valid unsigned 8-bit integer. Behavior is undefined when value is anything other than an unsigned 8-bit integer.

This function is also available under the writeUint8 alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt8(0x3, 0);
buf.writeUInt8(0x4, 1);
buf.writeUInt8(0x23, 2);
buf.writeUInt8(0x42, 3);

console.log(buf);
// Prints: <Buffer 03 04 23 42>
```
Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- Optional offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 1.
Returns number

writeUIntBE

writeUIntBE(value: number, offset: number, byteLength: number): number
Writes byteLength bytes of value to buf at the specified offsetas big-endian. Supports up to 48 bits of accuracy. Behavior is undefined when value is anything other than an unsigned integer.

This function is also available under the writeUintBE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(6);

buf.writeUIntBE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer 12 34 56 78 90 ab>
```
Note: as of Bun v0.1.2, this is not implemented yet.

Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to write. Must satisfy 0 < byteLength <= 6.
Returns number
writeUIntBE(value: number, offset: number, byteLength: number): number
Writes byteLength bytes of value to buf at the specified offsetas big-endian. Supports up to 48 bits of accuracy. Behavior is undefined when value is anything other than an unsigned integer.

This function is also available under the writeUintBE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(6);

buf.writeUIntBE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer 12 34 56 78 90 ab>
```
Note: as of Bun v0.1.2, this is not implemented yet.

Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to write. Must satisfy 0 < byteLength <= 6.
Returns number

writeUIntLE

writeUIntLE(value: number, offset: number, byteLength: number): number
Writes byteLength bytes of value to buf at the specified offsetas little-endian. Supports up to 48 bits of accuracy. Behavior is undefined when value is anything other than an unsigned integer.

This function is also available under the writeUintLE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(6);

buf.writeUIntLE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer ab 90 78 56 34 12>
```
Note: as of Bun v0.1.2, this is not implemented yet.

Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to write. Must satisfy 0 < byteLength <= 6.
Returns number
writeUIntLE(value: number, offset: number, byteLength: number): number
Writes byteLength bytes of value to buf at the specified offsetas little-endian. Supports up to 48 bits of accuracy. Behavior is undefined when value is anything other than an unsigned integer.

This function is also available under the writeUintLE alias.
```
import { Buffer } from 'buffer';

const buf = Buffer.allocUnsafe(6);

buf.writeUIntLE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer ab 90 78 56 34 12>
```
Note: as of Bun v0.1.2, this is not implemented yet.

Returns
offset plus the number of bytes written.
Parameters
- value: number
  
  Number to be written to buf.
- offset: number
  
  Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.
- byteLength: number
  
  Number of bytes to write. Must satisfy 0 < byteLength <= 6.
Returns number

writeUint16BE

writeUint16BE(value: number, offset?: number): number
Alias
Buffer.writeUInt16BE
Parameters
- value: number
- Optional offset: number
Returns number
writeUint16BE(value: number, offset?: number): number
Alias
Buffer.writeUInt16BE
Parameters
- value: number
- Optional offset: number
Returns number

writeUint16LE

writeUint16LE(value: number, offset?: number): number
Alias
Buffer.writeUInt16LE
Parameters
- value: number
- Optional offset: number
Returns number
writeUint16LE(value: number, offset?: number): number
Alias
Buffer.writeUInt16LE
Parameters
- value: number
- Optional offset: number
Returns number

writeUint32BE

writeUint32BE(value: number, offset?: number): number
Alias
Buffer.writeUInt32BE
Parameters
- value: number
- Optional offset: number
Returns number
writeUint32BE(value: number, offset?: number): number
Alias
Buffer.writeUInt32BE
Parameters
- value: number
- Optional offset: number
Returns number

writeUint32LE

writeUint32LE(value: number, offset?: number): number
Alias
Buffer.writeUInt32LE
Parameters
- value: number
- Optional offset: number
Returns number
writeUint32LE(value: number, offset?: number): number
Alias
Buffer.writeUInt32LE
Parameters
- value: number
- Optional offset: number
Returns number

writeUint8

writeUint8(value: number, offset?: number): number
Alias
Buffer.writeUInt8
Parameters
- value: number
- Optional offset: number
Returns number
writeUint8(value: number, offset?: number): number
Alias
Buffer.writeUInt8
Parameters
- value: number
- Optional offset: number
Returns number

writeUintBE

writeUintBE(value: number, offset: number, byteLength: number): number
Alias
Buffer.writeUIntBE
Parameters
- value: number
- offset: number
- byteLength: number
Returns number
writeUintBE(value: number, offset: number, byteLength: number): number
Alias
Buffer.writeUIntBE
Parameters
- value: number
- offset: number
- byteLength: number
Returns number

writeUintLE

writeUintLE(value: number, offset: number, byteLength: number): number
Alias
Buffer.writeUIntLE
Parameters
- value: number
- offset: number
- byteLength: number
Returns number
writeUintLE(value: number, offset: number, byteLength: number): number
Alias
Buffer.writeUIntLE
Parameters
- value: number
- offset: number
- byteLength: number
Returns number

Interface Buffer

Hierarchy

Index

Methods

Methods

compare

Parameters

target: Uint8Array

Optional targetStart: number

Optional targetEnd: number

Optional sourceStart: number

Optional sourceEnd: number

Returns 0 | 1 | -1

Parameters

target: Uint8Array

Optional targetStart: number

Optional targetEnd: number

Optional sourceStart: number

Optional sourceEnd: number

Returns 0 | 1 | -1

copy

Returns

Parameters

target: Uint8Array

Optional targetStart: number

Optional sourceStart: number

Optional sourceEnd: number

Returns number

Returns

Parameters

target: Uint8Array

Optional targetStart: number

Optional sourceStart: number

Optional sourceEnd: number

Returns number

entries

Returns IterableIterator<[number, number]>

Returns IterableIterator<[number, number]>

equals

Parameters

otherBuffer: Uint8Array

Returns boolean

Parameters

otherBuffer: Uint8Array

Returns boolean

fill

Returns

Parameters

value: string | number | Uint8Array

Optional offset: number

Optional end: number

Optional encoding: BufferEncoding

Returns "buffer".Buffer

Returns

Parameters

value: string | number | Uint8Array

Optional offset: number

Optional end: number

Optional encoding: BufferEncoding

Returns "buffer".Buffer

includes

Returns

Parameters

value: string | number | "buffer".Buffer

Optional byteOffset: number

Optional encoding: BufferEncoding

Returns boolean

Returns

Parameters

value: string | number | "buffer".Buffer

Optional byteOffset: number

Optional encoding: BufferEncoding

Returns boolean

indexOf

Returns

Parameters

value: string | number | Uint8Array

Optional byteOffset: number

Optional encoding: BufferEncoding

Returns number

`Optional` targetStart: number

`Optional` targetEnd: number

`Optional` sourceStart: number

`Optional` sourceEnd: number

`Optional` targetStart: number

`Optional` targetEnd: number

`Optional` sourceStart: number

`Optional` sourceEnd: number

`Optional` targetStart: number

`Optional` sourceStart: number

`Optional` sourceEnd: number

`Optional` targetStart: number

`Optional` sourceStart: number

`Optional` sourceEnd: number

`Optional` offset: number

`Optional` end: number

`Optional` encoding: BufferEncoding

`Optional` offset: number

`Optional` end: number

`Optional` encoding: BufferEncoding

`Optional` byteOffset: number

`Optional` encoding: BufferEncoding

`Optional` byteOffset: number

`Optional` encoding: BufferEncoding

`Optional` byteOffset: number

`Optional` encoding: BufferEncoding

`Optional` byteOffset: number

`Optional` encoding: BufferEncoding

`Optional` byteOffset: number

`Optional` encoding: BufferEncoding

`Optional` byteOffset: number

`Optional` encoding: BufferEncoding

`Optional` offset: number

`Optional` offset: number

`Optional` offset: number

`Optional` offset: number

`Optional` offset: number

`Optional` offset: number

`Optional` offset: number

`Optional` offset: number

`Optional` offset: number

`Optional` offset: number

`Optional` offset: number

`Optional` offset: number