Chain promises easily in node.js
Easily mix asynchronous and synchronous programming styles in node.js.
Mix promises into all the objects in your code base.
Songbird is built upon the bluebird promise library (hence the name).
If you have any questions about what methods the promises expose, go here to view the bluebird API.
Songbird requires node version 0.6.x or greater.
npm install songbird
Would you rather write this:
varUserfindOneidif err return callbackerr;usersetattributes;usersaveif err return callbackerr;console.log"Updated" updated;callbacknull updated;;;;
Or this, which behaves identically:
UserpromisefindOneidthen user →usersetattributesuserpromisesavethen consolelog"Updated"user
Using standard node callback-style APIs without Songbird, we write (from the fs docs):
fsreadFile'/etc/passwd'if err throw err;console.logdata;;
Using Songbird, we write:
Songbird makes it much easier to work with asynchronous methods in an interactive console, or REPL.
If you find yourself in an interactive session, you can require Songbird so that
you can use
> fs = require('fs');> require('songbird');> fs.promise.readFile('/etc/passwd', 'utf8').then (data) → data.get()
$ songbirdStarting Songbird node REPL...> fs = require('fs');> fs.promise.readFile('/etc/passwd', 'utf8').then(console.log)### User Database#...
Or for a CoffeeScript REPL:
$ songbird -c [or --coffee]Starting Songbird coffee REPL...coffee> fs = require 'fs'coffee> fs.promise.readFile('/etc/passwd', 'utf8').then console.log### User Database#...
Function.prototype so you can
use them directly as in:
readFile = require'fs'readFile;readFilepromise'/etc/passwd'thenconsole.log;
Object.prototype correctly so they
are not enumerable.
These proxy methods also ignore all getters, even those that may return functions. If you need to call a getter with Songbird that returns an asynchronous function, you can do:
func = objgetterfuncpromisecallobj args
Requiring the songbird library not only updates the Object and Function prototype, but also returns a Promise library in which you can carry out certain actions that aren't easily handled from the the promise property.
For example: you have a situation where you're dealing with multiple promises, but don't care what order they complete in.
Promise = require"songbird";Promisealltask1 task2 task3spread;
Normally when using
.then the code would be like:
Promise = require"songbird";Promisealltask1 task2 task3thenvar result1 = results0;var result2 = results1;var result3 = results2;;
For more information about the underlying bluebird promise API, the API docs are here.
The function should conform to node.js convention of accepting a callback as the last argument and calling that callback with error as the first argument and success value on the second argument.
Some people don't like libraries that mix in to Object.prototype and Function.prototype. If that's how you feel, then Songbird is probably not for you.
git clone git://github.com/duereg/songbird.gitnpm installnpm test
Songbird is written in coffeescript with
src/ compiled to
Tests are written with mocha and chai in
Run tests with
npm test which will also compile the coffeescript to
Pull requests are welcome. Please provide tests for your changes and features. Thanks!
(The MIT License)
Copyright (c) 2015 Matt Blair
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