Nearsighted Prank Master

    relike

    1.1.5 • Public • Published

    relike npmjs.com The MIT License npm downloads

    Simple promisify async or sync function with sane defaults. Lower level than promisify thing. Can be used to create promisify method.

    code climate standard code style travis build status coverage status dependency status

    You might also be interested in hybridify, hybridify-all, relike-all, letta

    Install

    npm i relike --save
    

    Usage

    For more use-cases see the tests

    const relike = require('relike')

    Note: It treat functions as asynchronous, based on is-async-function.

    Why you should be aware of that? Because if you give async function which don't have last argument called with some of the common-callback-names it will treat that function as synchronous and things may not work as expected.

    It's not a problem for most of the cases and for node's native packages, because that's a convention. So, the relike-all package successfuly can promisifies all of the fs functions for example, except fs.createReadStream and fs.createWriteStream which is normal.

    relike

    Runs fn in native Promise if available, or another provided in relike.Promise. If not given and not support for native Promise, it will use bluebird promise, but only on that enviroments that don't have support.

    Params

    • <fn> {Function}: Some async or synchronous function.
    • [...args] {Mixed}: Any number of any type of arguments, they are passed to fn.
    • returns {Promise}: Always native Promise if supported on enviroment.

    Example

    const fs = require('fs')
    const request = require('request')
    const relike = require('relike')
     
    relike(fs.readFile, 'package.json', 'utf-8').then(data => {
      console.log(JSON.parse(data).name) // => 'relike'
    })
     
    // handles multiple arguments by default (comes from `request`)
    relike(request, 'http://www.tunnckocore.tk/').then(result => {
      const [httpResponse, body] = result
    })

    .promisify

    Thin wrapper function around relike(). It accepts a function and returns a function, which when is invoked returns a Promise. Just like any other .promisify method, for example Bluebird.promisify.

    Params

    • fn {Function}: Some sync or async function to promisify.
    • [Promize] {Function}: Promise constructor to be used on enviroment where no support for native.
    • returns {Function}: Promisified function, which always return a Promise.

    Example

    var fs = require('fs')
    var relike = require('relike')
    var readFile = relike.promisify(fs.readFile)
     
    readFile('package.json', 'utf8')
      .then(JSON.parse)
      .then(data => {
        console.log(data.name) // => 'relike'
      })
     
    // also can promisify sync function
    var statFile = relike.promisify(fs.statSync)
    statFile('package.json')
      .then(function (stats) {
        console.log(stats.mtime)
      })

    .Promise

    While relike always trying to use native Promise if available in the enviroment, you can give a Promise constructor to be used on enviroment where there's no support - for example, old broswers or node's 0.10 version. By default, relike will use and include bluebird on old enviroments, as it is the fastest implementation of Promises. So, you are able to give Promise constructor, but it won't be used in modern enviroments - it always will use native Promise, you can't trick that. You can't give custom promise implementation to be used in any enviroment.

    Example

    var fs = require('fs')
    var relike = require('relike')
     
    relike.promisify.Promise = require('q') // using `Q` promise on node 0.10
    var readFile = relike.promisify(fs.readFile)
     
    readFile('package.json', 'utf8')
      .then(console.log, console.error)

    One way to pass a custom Promise constructor is as shown above. But the other way is passing it to .Promise of the promisified function, like that

    var fs = require('fs')
    var relike = require('relike')
    var statFile = relike.promisify(fs.stat)
     
    statFile.Promise = require('when') // using `when` promise on node 0.10
    statFile('package.json').then(console.log, console.error)

    One more thing, is that you can access the used Promise and can detect what promise is used. It is easy, just as promise.Promise and you'll get it. Or look for promise.___bluebirdPromise and promise.___customPromise properties. .___bluebirdPromise (yea, with three underscores in front) will be true if enviroment is old and you didn't provide promise constructor to .Promise.
    So, when you give constructor .__customPromise will be true and .___bluebirdPromise will be false.

    var fs = require('fs')
    var relike = require('relike')
     
    var promise = relike(fs.readFile, 'package.json', 'utf8')
    promise.then(JSON.parse).then(function (val) {
      console.log(val.name) // => 'relike'
    }, console.error)
     
    console.log(promise.Promise) // => used Promise constructor
    console.log(promise.___bluebirdPromise) // => `true` on old env, falsey otherwise
    console.log(promise.___customPromise) // => `true` when pass `.Promise`, falsey otherwise

    Or finally, you can pass Promise constructor as second argument to .promisify method. Like that

    const fs = require('fs')
    const relike = require('relike')
    const readFile = relike.promisify(fs.readFile, require('when'))
     
    const promise = readFile('index.js')
     
    console.log(promise.Promise) // => The `when` promise constructor, on old enviroments
    console.log(promise.___customPromise) // => `true` on old environments

    Related

    Contributing

    Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.
    But before doing anything, please read the CONTRIBUTING.md guidelines.

    Charlike Make Reagent new message to charlike freenode #charlike

    tunnckoCore.tk keybase tunnckoCore tunnckoCore npm tunnckoCore twitter tunnckoCore github

    Install

    npm i relike

    DownloadsWeekly Downloads

    21

    Version

    1.1.5

    License

    MIT

    Last publish

    Collaborators

    • vanchoy
    • tunnckocore