https://github.com/thenables/thenify

Promisify a callback-based function
https://github.com/thenables/thenify

Last synced: 3 days ago
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Promisify a callback-based function

• Host: GitHub
• URL: https://github.com/thenables/thenify
• Owner: thenables
• License: mit
• Created: 2014-12-17T06:05:12.000Z (about 10 years ago)
• Default Branch: master
• Last Pushed: 2020-10-25T09:01:40.000Z (over 4 years ago)
• Last Synced: 2025-02-05T12:06:42.149Z (10 days ago)
• Language: JavaScript
• Size: 20.5 KB
• Stars: 109
• Watchers: 4
• Forks: 19
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • Changelog: History.md
  • License: LICENSE

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• awesome-nodejs - thenify - Promisify a callback-based function.  (Repository / Control flow)

README

        

# thenify

[![NPM version][npm-image]][npm-url]

[![Build status][travis-image]][travis-url]

[![Test coverage][coveralls-image]][coveralls-url]

[![Dependency Status][david-image]][david-url]

[![License][license-image]][license-url]

[![Downloads][downloads-image]][downloads-url]

Promisify a callback-based function using [`any-promise`](https://github.com/kevinbeaty/any-promise).

- Preserves function names

- Uses a native promise implementation if available and tries to fall back to a promise implementation such as `bluebird`

- Converts multiple arguments from the callback into an `Array`, also support change the behavior by `options.multiArgs`

- Resulting function never deoptimizes

- Supports both callback and promise style

An added benefit is that `throw`n errors in that async function will be caught by the promise!

## API

### fn = thenify(fn, options)

Promisifies a function.

### Options

`options` are optional.

- `options.withCallback` - support both callback and promise style, default to `false`.

- `options.multiArgs` - change the behavior when callback have multiple arguments. default to `true`.

  - `true` - converts multiple arguments to an array

  - `false`- always use the first argument

  - `Array` - converts multiple arguments to an object with keys provided in `options.multiArgs`

- Turn async functions into promises

```js

var thenify = require('thenify');

var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {

  callback(null, a, b, c);

});

```

- Backward compatible with callback

```js

var thenify = require('thenify');

var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {

  callback(null, a, b, c);

}, { withCallback: true });

// somethingAsync(a, b, c).then(onFulfilled).catch(onRejected);

// somethingAsync(a, b, c, function () {});

```

or use `thenify.withCallback()`

```js

var thenify = require('thenify').withCallback;

var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {

  callback(null, a, b, c);

});

// somethingAsync(a, b, c).then(onFulfilled).catch(onRejected);

// somethingAsync(a, b, c, function () {});

```

- Always return the first argument in callback

```js

var thenify = require('thenify');

var promise = thenify(function (callback) {

  callback(null, 1, 2, 3);

}, { multiArgs: false });

// promise().then(function onFulfilled(value) {

//   assert.equal(value, 1);

// });

```

- Converts callback arguments to an object

```js

var thenify = require('thenify');

var promise = thenify(function (callback) {

  callback(null, 1, 2, 3);

}, { multiArgs: [ 'one', 'tow', 'three' ] });

// promise().then(function onFulfilled(value) {

//   assert.deepEqual(value, {

//     one: 1,

//     tow: 2,

//     three: 3

//   });

// });

```

[gitter-image]: https://badges.gitter.im/thenables/thenify.png

[gitter-url]: https://gitter.im/thenables/thenify

[npm-image]: https://img.shields.io/npm/v/thenify.svg?style=flat-square

[npm-url]: https://npmjs.org/package/thenify

[github-tag]: http://img.shields.io/github/tag/thenables/thenify.svg?style=flat-square

[github-url]: https://github.com/thenables/thenify/tags

[travis-image]: https://img.shields.io/travis/thenables/thenify.svg?style=flat-square

[travis-url]: https://travis-ci.org/thenables/thenify

[coveralls-image]: https://img.shields.io/coveralls/thenables/thenify.svg?style=flat-square

[coveralls-url]: https://coveralls.io/r/thenables/thenify

[david-image]: http://img.shields.io/david/thenables/thenify.svg?style=flat-square

[david-url]: https://david-dm.org/thenables/thenify

[license-image]: http://img.shields.io/npm/l/thenify.svg?style=flat-square

[license-url]: LICENSE

[downloads-image]: http://img.shields.io/npm/dm/thenify.svg?style=flat-square

[downloads-url]: https://npmjs.org/package/thenify