Promisify, basically, everything. Generator function, callback-style or synchronous function; sync function that returns child process, stream or observable; directly passed promise, stream or child process.
npm install always-promise> Promisify, basically, everything. Generator function, callback-style or synchronous function; sync function that returns child process, stream or observable; directly passed promise, stream or child process.
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npm i always-promise --save
API
> For more use-cases see the tests or try examples$3
> Promisify everything!-
{Function|GeneratorFunction|Stream|Promise} anything that merz accepts
- Prome {Function} custom promise module, which will be used for promisify-ing
+ you can also pass it through alwaysPromise.promise static property
+ or through promisifiedFn.promise static property
- return {Function} which returns promiseExample
`js
const promisify = require('always-promise')
`$3
> Static property on which you can pass custom promise constructor.
Actually same as argument.Example
`js
const fs = require('fs')//
q promise will be used if not native promise available
// but only in node <= 0.11.12
promisify.promise = require('q')
promisify(fs.readFile)('package.json', 'utf-8').then(data => {
console.log(JSON.parse(data).name)
})
`$3
> You also can pass custom promise module through static property of the returned promisified function. Example
`js
const fs = require('fs')
const readFile = promisify(fs.readFileSync)//
q promise will be used if not native promise available
// but only in node <= 0.11.12
readFile.promise = require('q')readFile('package.json', 'utf-8').then(data => {
console.log(JSON.parse(data).name)
})
`Examples
> Showing few examples how to can be used. See more in examples dir or tests$3
> Promisify-ing generator function, yielding readFile thunkjs
const fs = require('fs')function readThunk (fp) {
return function (done) {
fs.readFile(fp, 'utf8', done)
}
}
const readFile = promisify(function * (filepath) {
var data = yield read(filepath)
return JSON.parse(data)
})
readFile('package.json').then(function (json) {
console.log(json.name) // => 'always-promise'
}, console.error)
`$3
> Specific use-case which shows correct and working handling of optional arguments.js
promisify(JSON.stringify)({foo: 'bar'})
.then(data => {
console.log(data) //=> {"foo":"bar"}
}, console.error)// result with identation
promisify(JSON.stringify)({foo: 'bar'}, null, 2).then(function (data) {
console.log(data)
// =>
// {
// "foo": "bar"
// }
}, console.error)
`$3
> Again, showing correct handling of optinal arguments using native module.`js
const fs = require('fs')// callback function
promisify(fs.stat)('package.json')
.then(res => {
console.log(res.isFile()) //=> true
}, console.error)
// correct handling of optional arguments
promisify(fs.readFile)('package.json')
.then(buf => {
console.log(Buffer.isBuffer(buf)) //=> true
}, console.error)
// read json file and parse it,
// because it will be utf8 string
promisify(fs.readFileSync)('package.json', 'utf-8')
.then(JSON.parse)
.then(data => {
console.log(data.name) //=> 'always-callback'
}, console.error)
`$3
> If you pass more than two arguments to the callback, they will be flattened by default.js
promisify((one, two, three, cb) => {
cb(null, one, two, 33)
})(11, 22)
.then(res => {
console.log(Array.isArray(res)) //=> true
console.log(res) //=> [11, 22, 33]
}, console.error)
`
Related
- always-done: Handles completion and errors of anything!
- always-thunk: Create thunk from anything, works like . Transforms anything (callbacks, streams, promises, observables, child processes, sync and generator functions) to thunk.
- native-or-another: Always will expose native Promise if available, otherwise Bluebird but only if you don't give another promise module like q or promise or what you want.
- native-promise: Get native Promise` or falsey value if not available.[![tunnckocore.tk][author-www-img]][author-www-url] [![keybase tunnckocore][keybase-img]][keybase-url] [![tunnckoCore npm][author-npm-img]][author-npm-url] [![tunnckoCore twitter][author-twitter-img]][author-twitter-url] [![tunnckoCore github][author-github-img]][author-github-url]
[npmjs-url]: https://www.npmjs.com/package/always-promise
[npmjs-img]: https://img.shields.io/npm/v/always-promise.svg?label=always-promise
[license-url]: https://github.com/hybridables/always-promise/blob/master/LICENSE.md
[license-img]: https://img.shields.io/badge/license-MIT-blue.svg
[codeclimate-url]: https://codeclimate.com/github/hybridables/always-promise
[codeclimate-img]: https://img.shields.io/codeclimate/github/hybridables/always-promise.svg
[travis-url]: https://travis-ci.org/hybridables/always-promise
[travis-img]: https://img.shields.io/travis/hybridables/always-promise.svg
[coveralls-url]: https://coveralls.io/r/hybridables/always-promise
[coveralls-img]: https://img.shields.io/coveralls/hybridables/always-promise.svg
[david-url]: https://david-dm.org/hybridables/always-promise
[david-img]: https://img.shields.io/david/hybridables/always-promise.svg
[standard-url]: https://github.com/feross/standard
[standard-img]: https://img.shields.io/badge/code%20style-standard-brightgreen.svg
[author-www-url]: http://www.tunnckocore.tk
[author-www-img]: https://img.shields.io/badge/www-tunnckocore.tk-fe7d37.svg
[keybase-url]: https://keybase.io/tunnckocore
[keybase-img]: https://img.shields.io/badge/keybase-tunnckocore-8a7967.svg
[author-npm-url]: https://www.npmjs.com/~tunnckocore
[author-npm-img]: https://img.shields.io/badge/npm-~tunnckocore-cb3837.svg
[author-twitter-url]: https://twitter.com/tunnckoCore
[author-twitter-img]: https://img.shields.io/badge/twitter-@tunnckoCore-55acee.svg
[author-github-url]: https://github.com/tunnckoCore
[author-github-img]: https://img.shields.io/badge/github-@tunnckoCore-4183c4.svg
[freenode-url]: http://webchat.freenode.net/?channels=charlike
[freenode-img]: https://img.shields.io/badge/freenode-%23charlike-5654a4.svg
[new-message-url]: https://github.com/tunnckoCore/ama
[new-message-img]: https://img.shields.io/badge/ask%20me-anything-green.svg