es-promisify

es-promisify is a lightweight utility that converts Node.js callback-style functions to Promises, enabling you to use modern async/await syntax with legacy APIs.

Installation

You can install es-promisify via npm:

npm install es-promisify

Basic Usage

Here's a basic example of how to use es-promisify: More

• [x] cjs

const promisify = require('es-promisify')
const fs = require('fs')

// overload-1: promisify(fn, optionsObj)
const readFileAsync = promisify(fs.readFile, { timeout: '2s', bind: fs, cbType: 'errFirst', cache: true })

readFileAsync('example.txt', 'utf8')
  .then(data => console.log(data))
  .catch(err => console.error(err))

• [x] esm

import promisify from 'es-promisify'

const fn = (str: string, cb: (err, ...res) => void) => {
  setTimeout(() => {
    cb(null, str.toUpperCase())
  }, 2e3)
}

// overload-2: promisify(fn, timeout, optionsObj)
const result = await promisify(fn, 3e3)('upperCase this!!')

console.log(result) //=> UPPERCASE THIS!! after 2s

API

promisify(target, ...params)

• target (Function|Object): With callback-style to convert.
• ...params :
  • timeout (String|Number): Timeout for the promisified function.
  • bind (Object|String): The context for the function. 'this' = target
  • options (Object): Optional settings.
    • timeout, bind : Optional overload prop, instead of the above.
    • cbType (String): Callback type, either 'errFirst' or 'resultOnly'.
    • cache (Boolean): Whether to cache the promisified function.
• Returns: A Promise function.

Advance Usage

Promisify class

import { newPromisify, Promisify } from 'es-promisify'

// methode-1 
const promisify = newPromisify(customPromiseConstructor, defultOptions)
// return ↑ the handler binded to new instance

// methode-2
const P = new Promisify(/* same optional args */) 
//    ↑ the class instance
const promisify = P.handler.bind(P)
//        ↑ the handler

Contributing

Contributions are welcome! Please open an issue or submit a pull request on GitHub.

License

This project is licensed under the MIT License.