121 lines
3.7 KiB
Markdown
121 lines
3.7 KiB
Markdown
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# thenify
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[![NPM version][npm-image]][npm-url]
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[![Build status][travis-image]][travis-url]
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[![Test coverage][coveralls-image]][coveralls-url]
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[![Dependency Status][david-image]][david-url]
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[![License][license-image]][license-url]
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[![Downloads][downloads-image]][downloads-url]
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Promisify a callback-based function using [`any-promise`](https://github.com/kevinbeaty/any-promise).
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- Preserves function names
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- Uses a native promise implementation if available and tries to fall back to a promise implementation such as `bluebird`
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- Converts multiple arguments from the callback into an `Array`, also support change the behavior by `options.multiArgs`
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- Resulting function never deoptimizes
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- Supports both callback and promise style
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An added benefit is that `throw`n errors in that async function will be caught by the promise!
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## API
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### fn = thenify(fn, options)
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Promisifies a function.
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### Options
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`options` are optional.
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- `options.withCallback` - support both callback and promise style, default to `false`.
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- `options.multiArgs` - change the behavior when callback have multiple arguments. default to `true`.
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- `true` - converts multiple arguments to an array
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- `false`- always use the first argument
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- `Array` - converts multiple arguments to an object with keys provided in `options.multiArgs`
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- Turn async functions into promises
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```js
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var thenify = require('thenify');
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var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
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callback(null, a, b, c);
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});
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```
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- Backward compatible with callback
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```js
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var thenify = require('thenify');
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var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
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callback(null, a, b, c);
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}, { withCallback: true });
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// somethingAsync(a, b, c).then(onFulfilled).catch(onRejected);
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// somethingAsync(a, b, c, function () {});
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```
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or use `thenify.withCallback()`
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```js
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var thenify = require('thenify').withCallback;
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var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
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callback(null, a, b, c);
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});
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// somethingAsync(a, b, c).then(onFulfilled).catch(onRejected);
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// somethingAsync(a, b, c, function () {});
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```
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- Always return the first argument in callback
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```js
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var thenify = require('thenify');
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var promise = thenify(function (callback) {
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callback(null, 1, 2, 3);
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}, { multiArgs: false });
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// promise().then(function onFulfilled(value) {
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// assert.equal(value, 1);
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// });
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```
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- Converts callback arguments to an object
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```js
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var thenify = require('thenify');
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var promise = thenify(function (callback) {
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callback(null, 1, 2, 3);
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}, { multiArgs: [ 'one', 'tow', 'three' ] });
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// promise().then(function onFulfilled(value) {
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// assert.deepEqual(value, {
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// one: 1,
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// tow: 2,
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// three: 3
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// });
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// });
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```
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[gitter-image]: https://badges.gitter.im/thenables/thenify.png
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[gitter-url]: https://gitter.im/thenables/thenify
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[npm-image]: https://img.shields.io/npm/v/thenify.svg?style=flat-square
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[npm-url]: https://npmjs.org/package/thenify
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[github-tag]: http://img.shields.io/github/tag/thenables/thenify.svg?style=flat-square
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[github-url]: https://github.com/thenables/thenify/tags
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[travis-image]: https://img.shields.io/travis/thenables/thenify.svg?style=flat-square
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[travis-url]: https://travis-ci.org/thenables/thenify
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[coveralls-image]: https://img.shields.io/coveralls/thenables/thenify.svg?style=flat-square
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[coveralls-url]: https://coveralls.io/r/thenables/thenify
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[david-image]: http://img.shields.io/david/thenables/thenify.svg?style=flat-square
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[david-url]: https://david-dm.org/thenables/thenify
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[license-image]: http://img.shields.io/npm/l/thenify.svg?style=flat-square
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[license-url]: LICENSE
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[downloads-image]: http://img.shields.io/npm/dm/thenify.svg?style=flat-square
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[downloads-url]: https://npmjs.org/package/thenify
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