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119 lines
2.5 KiB
119 lines
2.5 KiB
# pify [![Build Status](https://travis-ci.org/sindresorhus/pify.svg?branch=master)](https://travis-ci.org/sindresorhus/pify) |
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> Promisify a callback-style function |
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## Install |
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``` |
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$ npm install --save pify |
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``` |
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## Usage |
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```js |
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const fs = require('fs'); |
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const pify = require('pify'); |
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// promisify a single function |
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pify(fs.readFile)('package.json', 'utf8').then(data => { |
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console.log(JSON.parse(data).name); |
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//=> 'pify' |
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}); |
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// or promisify all methods in a module |
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pify(fs).readFile('package.json', 'utf8').then(data => { |
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console.log(JSON.parse(data).name); |
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//=> 'pify' |
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}); |
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``` |
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## API |
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### pify(input, [promiseModule], [options]) |
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Returns a promise wrapped version of the supplied function or module. |
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#### input |
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Type: `function`, `object` |
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Callback-style function or module whose methods you want to promisify. |
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#### promiseModule |
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Type: `function` |
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Custom promise module to use instead of the native one. |
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Check out [`pinkie-promise`](https://github.com/floatdrop/pinkie-promise) if you need a tiny promise polyfill. |
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#### options |
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##### multiArgs |
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Type: `boolean` |
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Default: `false` |
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By default, the promisified function will only return the second argument from the callback, which works fine for most APIs. This option can be useful for modules like `request` that return multiple arguments. Turning this on will make it return an array of all arguments from the callback, excluding the error argument, instead of just the second argument. |
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```js |
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const request = require('request'); |
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const pify = require('pify'); |
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pify(request, {multiArgs: true})('https://sindresorhus.com').then(result => { |
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const [httpResponse, body] = result; |
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}); |
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``` |
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##### include |
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Type: `array` of (`string`|`regex`) |
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Methods in a module to promisify. Remaining methods will be left untouched. |
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##### exclude |
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Type: `array` of (`string`|`regex`) |
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Default: `[/.+Sync$/]` |
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Methods in a module **not** to promisify. Methods with names ending with `'Sync'` are excluded by default. |
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##### excludeMain |
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Type: `boolean` |
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Default: `false` |
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By default, if given module is a function itself, this function will be promisified. Turn this option on if you want to promisify only methods of the module. |
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```js |
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const pify = require('pify'); |
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function fn() { |
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return true; |
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} |
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fn.method = (data, callback) => { |
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setImmediate(() => { |
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callback(data, null); |
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}); |
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}; |
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// promisify methods but not fn() |
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const promiseFn = pify(fn, {excludeMain: true}); |
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if (promiseFn()) { |
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promiseFn.method('hi').then(data => { |
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console.log(data); |
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}); |
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} |
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``` |
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## License |
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MIT © [Sindre Sorhus](http://sindresorhus.com)
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