Function promisify

promisify<TCustom>(fn: "util".CustomPromisify<TCustom>): TCustom

Takes a function following the common error-first callback style, i.e. taking an (err, value) => ... callback as the last argument, and returns a version that returns promises.

const util = require('util');
const fs = require('fs');

const stat = util.promisify(fs.stat);
stat('.').then((stats) => {
  // Do something with `stats`
}).catch((error) => {
  // Handle the error.
});

Or, equivalently using async functions:

const util = require('util');
const fs = require('fs');

const stat = util.promisify(fs.stat);

async function callStat() {
  const stats = await stat('.');
  console.log(`This directory is owned by ${stats.uid}`);
}

If there is an original[util.promisify.custom] property present, promisifywill return its value, see Custom promisified functions.

promisify() assumes that original is a function taking a callback as its final argument in all cases. If original is not a function, promisify()will throw an error. If original is a function but its last argument is not an error-first callback, it will still be passed an error-first callback as its last argument.

Using promisify() on class methods or other methods that use this may not work as expected unless handled specially:

const util = require('util');

class Foo {
  constructor() {
    this.a = 42;
  }

  bar(callback) {
    callback(null, this.a);
  }
}

const foo = new Foo();

const naiveBar = util.promisify(foo.bar);
// TypeError: Cannot read property 'a' of undefined
// naiveBar().then(a => console.log(a));

naiveBar.call(foo).then((a) => console.log(a)); // '42'

const bindBar = naiveBar.bind(foo);
bindBar().then((a) => console.log(a)); // '42'

Type Parameters

TCustom extends Function

Parameters

fn: "util".CustomPromisify<TCustom>

Returns TCustom

promisify<TResult>(fn: ((callback: ((err: any, result: TResult) => void)) => void)): (() => Promise<TResult>)
Type Parameters
- TResult
Parameters
- fn: ((callback: ((err: any, result: TResult) => void)) => void)
  - - (callback: ((err: any, result: TResult) => void)): void
    - Parameters
      
      callback: ((err: any, result: TResult) => void)
      
      (err: any, result: TResult): void
      
      Parameters
      
      err: any
      
      result: TResult
      
      Returns void
      
      Returns void
Returns (() => Promise<TResult>)
- - (): Promise<TResult>
  - Returns Promise<TResult>
promisify(fn: ((callback: ((err?: any) => void)) => void)): (() => Promise<void>)
Parameters
- fn: ((callback: ((err?: any) => void)) => void)
  - - (callback: ((err?: any) => void)): void
    - Parameters
      
      callback: ((err?: any) => void)
      
      (err?: any): void
      
      Parameters
      
      Optional err: any
      
      Returns void
      
      Returns void
Returns (() => Promise<void>)
- - (): Promise<void>
  - Returns Promise<void>
promisify<T1, TResult>(fn: ((arg1: T1, callback: ((err: any, result: TResult) => void)) => void)): ((arg1: T1) => Promise<TResult>)
Type Parameters
- T1
- TResult
Parameters
- fn: ((arg1: T1, callback: ((err: any, result: TResult) => void)) => void)
  - - (arg1: T1, callback: ((err: any, result: TResult) => void)): void
    - Parameters
      
      arg1: T1
      
      callback: ((err: any, result: TResult) => void)
      
      (err: any, result: TResult): void
      
      Parameters
      
      err: any
      
      result: TResult
      
      Returns void
      
      Returns void
Returns ((arg1: T1) => Promise<TResult>)
- - (arg1: T1): Promise<TResult>
  - Parameters
    - arg1: T1
    Returns Promise<TResult>
promisify<T1>(fn: ((arg1: T1, callback: ((err?: any) => void)) => void)): ((arg1: T1) => Promise<void>)
Type Parameters
- T1
Parameters
- fn: ((arg1: T1, callback: ((err?: any) => void)) => void)
  - - (arg1: T1, callback: ((err?: any) => void)): void
    - Parameters
      
      arg1: T1
      
      callback: ((err?: any) => void)
      
      (err?: any): void
      
      Parameters
      
      Optional err: any
      
      Returns void
      
      Returns void
Returns ((arg1: T1) => Promise<void>)
- - (arg1: T1): Promise<void>
  - Parameters
    - arg1: T1
    Returns Promise<void>
promisify<T1, T2, TResult>(fn: ((arg1: T1, arg2: T2, callback: ((err: any, result: TResult) => void)) => void)): ((arg1: T1, arg2: T2) => Promise<TResult>)
Type Parameters
- T1
- T2
- TResult
Parameters
- fn: ((arg1: T1, arg2: T2, callback: ((err: any, result: TResult) => void)) => void)
  - - (arg1: T1, arg2: T2, callback: ((err: any, result: TResult) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      callback: ((err: any, result: TResult) => void)
      
      (err: any, result: TResult): void
      
      Parameters
      
      err: any
      
      result: TResult
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2) => Promise<TResult>)
- - (arg1: T1, arg2: T2): Promise<TResult>
  - Parameters
    - arg1: T1
    - arg2: T2
    Returns Promise<TResult>
promisify<T1, T2>(fn: ((arg1: T1, arg2: T2, callback: ((err?: any) => void)) => void)): ((arg1: T1, arg2: T2) => Promise<void>)
Type Parameters
- T1
- T2
Parameters
- fn: ((arg1: T1, arg2: T2, callback: ((err?: any) => void)) => void)
  - - (arg1: T1, arg2: T2, callback: ((err?: any) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      callback: ((err?: any) => void)
      
      (err?: any): void
      
      Parameters
      
      Optional err: any
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2) => Promise<void>)
- - (arg1: T1, arg2: T2): Promise<void>
  - Parameters
    - arg1: T1
    - arg2: T2
    Returns Promise<void>
promisify<T1, T2, T3, TResult>(fn: ((arg1: T1, arg2: T2, arg3: T3, callback: ((err: any, result: TResult) => void)) => void)): ((arg1: T1, arg2: T2, arg3: T3) => Promise<TResult>)
Type Parameters
- T1
- T2
- T3
- TResult
Parameters
- fn: ((arg1: T1, arg2: T2, arg3: T3, callback: ((err: any, result: TResult) => void)) => void)
  - - (arg1: T1, arg2: T2, arg3: T3, callback: ((err: any, result: TResult) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      arg3: T3
      
      callback: ((err: any, result: TResult) => void)
      
      (err: any, result: TResult): void
      
      Parameters
      
      err: any
      
      result: TResult
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2, arg3: T3) => Promise<TResult>)
- - (arg1: T1, arg2: T2, arg3: T3): Promise<TResult>
  - Parameters
    - arg1: T1
    - arg2: T2
    - arg3: T3
    Returns Promise<TResult>
promisify<T1, T2, T3>(fn: ((arg1: T1, arg2: T2, arg3: T3, callback: ((err?: any) => void)) => void)): ((arg1: T1, arg2: T2, arg3: T3) => Promise<void>)
Type Parameters
- T1
- T2
- T3
Parameters
- fn: ((arg1: T1, arg2: T2, arg3: T3, callback: ((err?: any) => void)) => void)
  - - (arg1: T1, arg2: T2, arg3: T3, callback: ((err?: any) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      arg3: T3
      
      callback: ((err?: any) => void)
      
      (err?: any): void
      
      Parameters
      
      Optional err: any
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2, arg3: T3) => Promise<void>)
- - (arg1: T1, arg2: T2, arg3: T3): Promise<void>
  - Parameters
    - arg1: T1
    - arg2: T2
    - arg3: T3
    Returns Promise<void>
promisify<T1, T2, T3, T4, TResult>(fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, callback: ((err: any, result: TResult) => void)) => void)): ((arg1: T1, arg2: T2, arg3: T3, arg4: T4) => Promise<TResult>)
Type Parameters
- T1
- T2
- T3
- T4
- TResult
Parameters
- fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, callback: ((err: any, result: TResult) => void)) => void)
  - - (arg1: T1, arg2: T2, arg3: T3, arg4: T4, callback: ((err: any, result: TResult) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      arg3: T3
      
      arg4: T4
      
      callback: ((err: any, result: TResult) => void)
      
      (err: any, result: TResult): void
      
      Parameters
      
      err: any
      
      result: TResult
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2, arg3: T3, arg4: T4) => Promise<TResult>)
- - (arg1: T1, arg2: T2, arg3: T3, arg4: T4): Promise<TResult>
  - Parameters
    - arg1: T1
    - arg2: T2
    - arg3: T3
    - arg4: T4
    Returns Promise<TResult>
promisify<T1, T2, T3, T4>(fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, callback: ((err?: any) => void)) => void)): ((arg1: T1, arg2: T2, arg3: T3, arg4: T4) => Promise<void>)
Type Parameters
- T1
- T2
- T3
- T4
Parameters
- fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, callback: ((err?: any) => void)) => void)
  - - (arg1: T1, arg2: T2, arg3: T3, arg4: T4, callback: ((err?: any) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      arg3: T3
      
      arg4: T4
      
      callback: ((err?: any) => void)
      
      (err?: any): void
      
      Parameters
      
      Optional err: any
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2, arg3: T3, arg4: T4) => Promise<void>)
- - (arg1: T1, arg2: T2, arg3: T3, arg4: T4): Promise<void>
  - Parameters
    - arg1: T1
    - arg2: T2
    - arg3: T3
    - arg4: T4
    Returns Promise<void>
promisify<T1, T2, T3, T4, T5, TResult>(fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, callback: ((err: any, result: TResult) => void)) => void)): ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5) => Promise<TResult>)
Type Parameters
- T1
- T2
- T3
- T4
- T5
- TResult
Parameters
- fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, callback: ((err: any, result: TResult) => void)) => void)
  - - (arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, callback: ((err: any, result: TResult) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      arg3: T3
      
      arg4: T4
      
      arg5: T5
      
      callback: ((err: any, result: TResult) => void)
      
      (err: any, result: TResult): void
      
      Parameters
      
      err: any
      
      result: TResult
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5) => Promise<TResult>)
- - (arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5): Promise<TResult>
  - Parameters
    - arg1: T1
    - arg2: T2
    - arg3: T3
    - arg4: T4
    - arg5: T5
    Returns Promise<TResult>
promisify<T1, T2, T3, T4, T5>(fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, callback: ((err?: any) => void)) => void)): ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5) => Promise<void>)
Type Parameters
- T1
- T2
- T3
- T4
- T5
Parameters
- fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, callback: ((err?: any) => void)) => void)
  - - (arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, callback: ((err?: any) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      arg3: T3
      
      arg4: T4
      
      arg5: T5
      
      callback: ((err?: any) => void)
      
      (err?: any): void
      
      Parameters
      
      Optional err: any
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5) => Promise<void>)
- - (arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5): Promise<void>
  - Parameters
    - arg1: T1
    - arg2: T2
    - arg3: T3
    - arg4: T4
    - arg5: T5
    Returns Promise<void>
promisify(fn: Function): Function
Parameters
- fn: Function
Returns Function
promisify<TCustom>(fn: "util".CustomPromisify<TCustom>): TCustom

Takes a function following the common error-first callback style, i.e. taking an (err, value) => ... callback as the last argument, and returns a version that returns promises.

const util = require('util');
const fs = require('fs');

const stat = util.promisify(fs.stat);
stat('.').then((stats) => {
  // Do something with `stats`
}).catch((error) => {
  // Handle the error.
});

Or, equivalently using async functions:

const util = require('util');
const fs = require('fs');

const stat = util.promisify(fs.stat);

async function callStat() {
  const stats = await stat('.');
  console.log(`This directory is owned by ${stats.uid}`);
}

If there is an original[util.promisify.custom] property present, promisifywill return its value, see Custom promisified functions.

Using promisify() on class methods or other methods that use this may not work as expected unless handled specially:

const util = require('util');

class Foo {
  constructor() {
    this.a = 42;
  }

  bar(callback) {
    callback(null, this.a);
  }
}

const foo = new Foo();

const naiveBar = util.promisify(foo.bar);
// TypeError: Cannot read property 'a' of undefined
// naiveBar().then(a => console.log(a));

naiveBar.call(foo).then((a) => console.log(a)); // '42'

const bindBar = naiveBar.bind(foo);
bindBar().then((a) => console.log(a)); // '42'

Type Parameters

TCustom extends Function

Parameters

fn: "util".CustomPromisify<TCustom>

Returns TCustom

promisify<TResult>(fn: ((callback: ((err: any, result: TResult) => void)) => void)): (() => Promise<TResult>)
Type Parameters
- TResult
Parameters
- fn: ((callback: ((err: any, result: TResult) => void)) => void)
  - - (callback: ((err: any, result: TResult) => void)): void
    - Parameters
      
      callback: ((err: any, result: TResult) => void)
      
      (err: any, result: TResult): void
      
      Parameters
      
      err: any
      
      result: TResult
      
      Returns void
      
      Returns void
Returns (() => Promise<TResult>)
- - (): Promise<TResult>
  - Returns Promise<TResult>
promisify(fn: ((callback: ((err?: any) => void)) => void)): (() => Promise<void>)
Parameters
- fn: ((callback: ((err?: any) => void)) => void)
  - - (callback: ((err?: any) => void)): void
    - Parameters
      
      callback: ((err?: any) => void)
      
      (err?: any): void
      
      Parameters
      
      Optional err: any
      
      Returns void
      
      Returns void
Returns (() => Promise<void>)
- - (): Promise<void>
  - Returns Promise<void>
promisify<T1, TResult>(fn: ((arg1: T1, callback: ((err: any, result: TResult) => void)) => void)): ((arg1: T1) => Promise<TResult>)
Type Parameters
- T1
- TResult
Parameters
- fn: ((arg1: T1, callback: ((err: any, result: TResult) => void)) => void)
  - - (arg1: T1, callback: ((err: any, result: TResult) => void)): void
    - Parameters
      
      arg1: T1
      
      callback: ((err: any, result: TResult) => void)
      
      (err: any, result: TResult): void
      
      Parameters
      
      err: any
      
      result: TResult
      
      Returns void
      
      Returns void
Returns ((arg1: T1) => Promise<TResult>)
- - (arg1: T1): Promise<TResult>
  - Parameters
    - arg1: T1
    Returns Promise<TResult>
promisify<T1>(fn: ((arg1: T1, callback: ((err?: any) => void)) => void)): ((arg1: T1) => Promise<void>)
Type Parameters
- T1
Parameters
- fn: ((arg1: T1, callback: ((err?: any) => void)) => void)
  - - (arg1: T1, callback: ((err?: any) => void)): void
    - Parameters
      
      arg1: T1
      
      callback: ((err?: any) => void)
      
      (err?: any): void
      
      Parameters
      
      Optional err: any
      
      Returns void
      
      Returns void
Returns ((arg1: T1) => Promise<void>)
- - (arg1: T1): Promise<void>
  - Parameters
    - arg1: T1
    Returns Promise<void>
promisify<T1, T2, TResult>(fn: ((arg1: T1, arg2: T2, callback: ((err: any, result: TResult) => void)) => void)): ((arg1: T1, arg2: T2) => Promise<TResult>)
Type Parameters
- T1
- T2
- TResult
Parameters
- fn: ((arg1: T1, arg2: T2, callback: ((err: any, result: TResult) => void)) => void)
  - - (arg1: T1, arg2: T2, callback: ((err: any, result: TResult) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      callback: ((err: any, result: TResult) => void)
      
      (err: any, result: TResult): void
      
      Parameters
      
      err: any
      
      result: TResult
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2) => Promise<TResult>)
- - (arg1: T1, arg2: T2): Promise<TResult>
  - Parameters
    - arg1: T1
    - arg2: T2
    Returns Promise<TResult>
promisify<T1, T2>(fn: ((arg1: T1, arg2: T2, callback: ((err?: any) => void)) => void)): ((arg1: T1, arg2: T2) => Promise<void>)
Type Parameters
- T1
- T2
Parameters
- fn: ((arg1: T1, arg2: T2, callback: ((err?: any) => void)) => void)
  - - (arg1: T1, arg2: T2, callback: ((err?: any) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      callback: ((err?: any) => void)
      
      (err?: any): void
      
      Parameters
      
      Optional err: any
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2) => Promise<void>)
- - (arg1: T1, arg2: T2): Promise<void>
  - Parameters
    - arg1: T1
    - arg2: T2
    Returns Promise<void>
promisify<T1, T2, T3, TResult>(fn: ((arg1: T1, arg2: T2, arg3: T3, callback: ((err: any, result: TResult) => void)) => void)): ((arg1: T1, arg2: T2, arg3: T3) => Promise<TResult>)
Type Parameters
- T1
- T2
- T3
- TResult
Parameters
- fn: ((arg1: T1, arg2: T2, arg3: T3, callback: ((err: any, result: TResult) => void)) => void)
  - - (arg1: T1, arg2: T2, arg3: T3, callback: ((err: any, result: TResult) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      arg3: T3
      
      callback: ((err: any, result: TResult) => void)
      
      (err: any, result: TResult): void
      
      Parameters
      
      err: any
      
      result: TResult
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2, arg3: T3) => Promise<TResult>)
- - (arg1: T1, arg2: T2, arg3: T3): Promise<TResult>
  - Parameters
    - arg1: T1
    - arg2: T2
    - arg3: T3
    Returns Promise<TResult>
promisify<T1, T2, T3>(fn: ((arg1: T1, arg2: T2, arg3: T3, callback: ((err?: any) => void)) => void)): ((arg1: T1, arg2: T2, arg3: T3) => Promise<void>)
Type Parameters
- T1
- T2
- T3
Parameters
- fn: ((arg1: T1, arg2: T2, arg3: T3, callback: ((err?: any) => void)) => void)
  - - (arg1: T1, arg2: T2, arg3: T3, callback: ((err?: any) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      arg3: T3
      
      callback: ((err?: any) => void)
      
      (err?: any): void
      
      Parameters
      
      Optional err: any
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2, arg3: T3) => Promise<void>)
- - (arg1: T1, arg2: T2, arg3: T3): Promise<void>
  - Parameters
    - arg1: T1
    - arg2: T2
    - arg3: T3
    Returns Promise<void>
promisify<T1, T2, T3, T4, TResult>(fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, callback: ((err: any, result: TResult) => void)) => void)): ((arg1: T1, arg2: T2, arg3: T3, arg4: T4) => Promise<TResult>)
Type Parameters
- T1
- T2
- T3
- T4
- TResult
Parameters
- fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, callback: ((err: any, result: TResult) => void)) => void)
  - - (arg1: T1, arg2: T2, arg3: T3, arg4: T4, callback: ((err: any, result: TResult) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      arg3: T3
      
      arg4: T4
      
      callback: ((err: any, result: TResult) => void)
      
      (err: any, result: TResult): void
      
      Parameters
      
      err: any
      
      result: TResult
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2, arg3: T3, arg4: T4) => Promise<TResult>)
- - (arg1: T1, arg2: T2, arg3: T3, arg4: T4): Promise<TResult>
  - Parameters
    - arg1: T1
    - arg2: T2
    - arg3: T3
    - arg4: T4
    Returns Promise<TResult>
promisify<T1, T2, T3, T4>(fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, callback: ((err?: any) => void)) => void)): ((arg1: T1, arg2: T2, arg3: T3, arg4: T4) => Promise<void>)
Type Parameters
- T1
- T2
- T3
- T4
Parameters
- fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, callback: ((err?: any) => void)) => void)
  - - (arg1: T1, arg2: T2, arg3: T3, arg4: T4, callback: ((err?: any) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      arg3: T3
      
      arg4: T4
      
      callback: ((err?: any) => void)
      
      (err?: any): void
      
      Parameters
      
      Optional err: any
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2, arg3: T3, arg4: T4) => Promise<void>)
- - (arg1: T1, arg2: T2, arg3: T3, arg4: T4): Promise<void>
  - Parameters
    - arg1: T1
    - arg2: T2
    - arg3: T3
    - arg4: T4
    Returns Promise<void>
promisify<T1, T2, T3, T4, T5, TResult>(fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, callback: ((err: any, result: TResult) => void)) => void)): ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5) => Promise<TResult>)
Type Parameters
- T1
- T2
- T3
- T4
- T5
- TResult
Parameters
- fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, callback: ((err: any, result: TResult) => void)) => void)
  - - (arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, callback: ((err: any, result: TResult) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      arg3: T3
      
      arg4: T4
      
      arg5: T5
      
      callback: ((err: any, result: TResult) => void)
      
      (err: any, result: TResult): void
      
      Parameters
      
      err: any
      
      result: TResult
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5) => Promise<TResult>)
- - (arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5): Promise<TResult>
  - Parameters
    - arg1: T1
    - arg2: T2
    - arg3: T3
    - arg4: T4
    - arg5: T5
    Returns Promise<TResult>
promisify<T1, T2, T3, T4, T5>(fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, callback: ((err?: any) => void)) => void)): ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5) => Promise<void>)
Type Parameters
- T1
- T2
- T3
- T4
- T5
Parameters
- fn: ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, callback: ((err?: any) => void)) => void)
  - - (arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5, callback: ((err?: any) => void)): void
    - Parameters
      
      arg1: T1
      
      arg2: T2
      
      arg3: T3
      
      arg4: T4
      
      arg5: T5
      
      callback: ((err?: any) => void)
      
      (err?: any): void
      
      Parameters
      
      Optional err: any
      
      Returns void
      
      Returns void
Returns ((arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5) => Promise<void>)
- - (arg1: T1, arg2: T2, arg3: T3, arg4: T4, arg5: T5): Promise<void>
  - Parameters
    - arg1: T1
    - arg2: T2
    - arg3: T3
    - arg4: T4
    - arg5: T5
    Returns Promise<void>
promisify(fn: Function): Function
Parameters
- fn: Function
Returns Function

Function promisify

Type Parameters

TCustom extends Function

Parameters

fn: "util".CustomPromisify<TCustom>

Returns TCustom

Type Parameters

TResult

Parameters

fn: ((callback: ((err: any, result: TResult) => void)) => void)

Parameters

callback: ((err: any, result: TResult) => void)

Parameters

err: any

result: TResult

Returns void

Returns void

Returns (() => Promise<TResult>)

Returns Promise<TResult>

Parameters

fn: ((callback: ((err?: any) => void)) => void)

Parameters

callback: ((err?: any) => void)

Parameters

Optional err: any

Returns void

Returns void

Returns (() => Promise<void>)

Returns Promise<void>

Type Parameters

T1

TResult

Parameters

fn: ((arg1: T1, callback: ((err: any, result: TResult) => void)) => void)

Parameters

arg1: T1

callback: ((err: any, result: TResult) => void)

Parameters

err: any

result: TResult

Returns void

Returns void

Returns ((arg1: T1) => Promise<TResult>)

Parameters

arg1: T1

Returns Promise<TResult>

Type Parameters

T1

Parameters

fn: ((arg1: T1, callback: ((err?: any) => void)) => void)

Parameters

arg1: T1

callback: ((err?: any) => void)

Parameters

Optional err: any

Returns void

Returns void

Returns ((arg1: T1) => Promise<void>)

Parameters

arg1: T1

Returns Promise<void>

Type Parameters

T1

T2

TResult

Parameters

fn: ((arg1: T1, arg2: T2, callback: ((err: any, result: TResult) => void)) => void)

Parameters

arg1: T1

arg2: T2

callback: ((err: any, result: TResult) => void)

Parameters

err: any

result: TResult

Returns void

Returns void

Returns ((arg1: T1, arg2: T2) => Promise<TResult>)

Parameters

arg1: T1

arg2: T2

`Optional` err: any

`Optional` err: any

`Optional` err: any

`Optional` err: any