d-mobilelab / promiselite

PromiseLite is a light, browser-friendly implementation of JavaScript promises.

promiselite

[!!!] This repository has been deprecated, we suggest to use https://github.com/taylorhakes/promise-polyfill instead

PromiseLite is a light, browser-friendly implementation of JavaScript promises.

Installation

NPM

npm install --save promiselite

You can found the library ready for production on node_modules/promiselite/dist/dist.js

Bower

bower install --save promiselite

You can found the library ready for production on bower_components/promiselite/dist/dist.js

Documentation

To read documentation, go to:

http://d-mobilelab.github.io/promiselite/1.3.0

Replace 1.3.0 with the version of the documentation you want to read.

Usage

Executors, then and fail

See the documentation of JavaScript Promise here.

The name fail was used instead of catch for compatibility reasons. since some browsers do not allow bare keywords in dot notation.

Example

#!JavaScript

var p = new PromiseLite(function(resolve, reject){
    setTimeout(function(){
        if (Math.random() > 0.5){
            resolve('It worked!');
        } else {
            reject('It failed!');
        }
    });
}).then(function(value){
    console.info('Yay! ' + value); // outputs 'Yay! It worked!'
}).fail(function(reason){
    console.error('Ops! ' + reason); // outputs 'Ops! It failed!'
});;

Forced blocks

The method force corresponds to a finally block applied to a chain of promises. It is executed both when a PromiseLite instance is both in a fulfilled or rejected state.

The name force was used instead of finally for compatibility reasons since some browsers do not allow bare keywords in dot notation.

Example

#!javascript

var p = new PromiseLite();

p.then(function(value){
   // do something if resolved
   // i.e. read data from an open file
}).fail(function(reason){
   // do something if rejected (or if an Error is raised)
   // i.e. show an error message on screen - "missing file"
}).force(function(){
   // do something both if resolved or rejected
   // i.e. close the file
});

Resolving a Promise created without an executor

#!JavaScript

var p = new PromiseLite();

p.then(function(value){
    console.log('The answer is ' + value);
});

// since p has no executor, it won't be resolved until we invoke p.resolve

p.resolve(42); // outputs 'The answer is 42'

PromiseLite.all

PromiseLite.all takes an Array of PromiseLite as argument and is resolved if and only if all such promises are fulfilled.

#!javascript

var p1 = new PromiseLite();
var p2 = new PromiseLite();
var p3 = new PromiseLite();

var pAll = new PromiseLite.all([p1, p2, p3]);

PromiseLite.race

PromiseLite.race takes an Array of PromiseLite as argument, then

• if the first promise that is settled is fulfilled, the promise returned by PromiseLite.race is resolved

• if the first promise that is settled is rejected, the promise returned by PromiseLite.race is rejected

#!javascript

var p1 = new PromiseLite();
var p2 = new PromiseLite();
var p3 = new PromiseLite();

var pRace = new PromiseLite.race([p1, p2, p3]);

PromiseLite.any

PromiseLite.any takes an Array of PromiseLite as argument, then

• if at least one of such promises is fulfilled, the promise returned by PromiseLite.any is resolved

• if all the promises are rejected, the promise returned by PromiseLite.any is rejected

#!javascript

var p1 = new PromiseLite();
var p2 = new PromiseLite();
var p3 = new PromiseLite();

var pAny = new PromiseLite.any([p1, p2, p3]);