README.md

relike-value

Create promise from sync, async, string, number, array and so on. Handle completion (results) and errors gracefully! Built on top of relike, used by redolent to build robust (hybrid) APIs.

What's the difference?

What's the difference between me and you?!
–– Dr Dre feat. Eminem & X-Zibit - Whats the Difference, https://youtu.be/8y5MjguI-pM

What's the difference between this module, relike and redolent?
–– Simply, almost nothing.

1. This one accepts everything and returns Promise. But it is little bit tricky:

• if you pass only one non-function argument to it, it will pass it to promise
• if you pass more that one arguments to it, it will create array from them and pass it to promise
• if you pass function as first argument, next arguments will be passed to this function

2. relike one just accept sync or async function which is executed immediately with next arguments, after that it returns Promise.
3. redolent accepts everything and returns function, which when is executed it returns Promise. Above things applies here, because it is on top of relike-value.

Notice: Both relike and relike-value direcly executes first argument (if function) and returns Promise.

Install

npm i relike-value --save

Usage

For more use-cases see the tests

const relikeValue = require('relike-value')

relikeValue

Will try to promisify fn with native Promise, otherwise will use Bluebird or you can give different promise module to relikeValue.promise, for example pinkie.

• [args...] {Anything} any number of any type from string to function (number, array, boolean, etc)
• return {Promise} promise

Example

const fs = require('fs')
const request = require('request')
const relikeValue = require('relike-value')

relikeValue(fs.readFile, 'package.json', 'utf-8').then(data => {
  console.log(JSON.parse(data).name)
})

// promisify sync function
relikeValue(fs.readFileSync, 'package.json', 'utf-8')
.then(JSON.parse)
.then(res => {
  console.log(res.name)
})

// handles multiple arguments by default (comes from `request`)
relikeValue(request, 'http://www.tunnckocore.tk/').then(result => {
  const [httpResponse, body] = result
})

relikeValue.promise

Static property on which you can pass custom Promise module to use, e.g. Q constructor.

Example

const fs = require('fs')
const relikeValue = require('relike-value')

// `q` promise will be used if not native promise available
// but only in node <= 0.11.12
relikeValue.promise = require('q')
relikeValue(fs.readFile, 'package.json', 'utf-8').then(data => {
  console.log(JSON.parse(data).name)
})

Access Promise constructor

You can access the used Promise constructor for promisify-ing from promise.Prome

Example

const fs = require('fs')
const relikeValue = require('relike-value')

// use `pinkie` promise if not native promise available
// but only in node <= 0.11.12
relikeValue.promise = require('pinkie')

const promise = relikeValue(fs.readFile, 'package.json', 'utf8')

console.log(promise.Prome)
//=> will be `pinkie` promise constructor (only in node <= 0.11.12)
console.log(promise.Prome.___customPromise) //=> true (only on node <= 0.11.12)
console.log(promise.___customPromise) //=> true (only on node <= 0.11.12)

promise
  .then(JSON.parse)
  .then(data => {
    console.log(data.name) //=> `relike-value`
  })

Promise from any type

Any number of any type of arguments can be given - String, Stream, Null, Boolean, Number and etc.

Example

const relikeValue = require('relike-value')

var promise = relikeValue('foo bar baz').then(function (str) {
  console.log(str) // => 'foo bar baz'
}, console.error)

relikeValue(false).then(function (bool) {
  console.log(bool) // => false

  return relikeValue(null).then(function (empty) {
  console.log(empty) // => null
  })
}, console.error)

relikeValue('foo', 123, [1, 2], {a: 'b'}).then(function (arr) {
  console.log(arr) // => ['foo', 123, [1, 2], {a: 'b'}]
}, console.error)

Related

• always-done: Handles completion and errors of anything!
• 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.
• always-thunk: Thunkify, 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.
• always-generator: Generatorify, basically, everything. Async, callback-style or synchronous function; sync function that returns child process, stream or observable; directly passed promise, stream or child process.
• 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.
• relike: Simple promisify a callback-style function with sane defaults. Support promisify-ing sync functions.
• relike-all: Promisify all functions in an object, using relike.

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