Showing posts with label ngQueue. Show all posts
Showing posts with label ngQueue. Show all posts


August 02, 2017
ngQueue is an AngularJS module that helps you to handle routine sync/async queue task in AngularJS with ease. Demo

Getting started

Include the ngQueue module with AngularJS script in your page.
 <script src="//"></script>  
 <script src=""></script>  
Add ngQueue to your app module's dependency.
 angular.module('myApp', ['ngQueue']);  

Install with Bower

 bower install ngQueue  


$queueFactory(limit, deferred)

  • limit - The maximum concurrent task for the queue. Default value 1.
  • deferred - If true, queued tasks are padded with a very small time interval, allowlling the browser to update UIs or respond to user interactions. Default value false. More about deferred option.
Start with $queueFactory to create a queue you'll be working with.
 // Create a queue with concurrent task quota of 2  
 var queue1 = $queueFactory(2);  
 // Create a deferred queue  
 var queue2 = $queueFactory(1, true);  
Now you are ready to play with Queue instance APIs.

Queue instance APIs

enqueue(fn, context, args)

Enqueue a task(fn) with specified context(optional) and arguments(optional). Returns a task handle for you to remove the task from the queue before it gets dequeued with remove. The task can be either asynchronous or synchronous.
Synchronous tasks work just like usual function call.
 // synchronous task //  
 queue.enqueue(function (inA, inB, inC) {  
  console.log(this); // {name: "context"}  
  console.log(inA, inB, inC); // hello world !  
 }, {name: 'context'}, ['hello', 'world', '!']);  
Return an $q promise in the task function to make it asynchronous.
 // asynchronous task //  
 // $timeout delay  
 queue.enqueue(function () {  
  var dfd = $q.defer();  
  $timeout(function () {  
   // or dfd.reject()  
  }, 100);  
  return dfd.promise;  
 // $http request  
 queue.enqueue(function () {  
  return $http.get('/some/api/call')  
   .success(function () {  
    // do something if success  
   .error(function () {  
    // do something if error  
Remove a task from the queue before it gets dequeued. taskHandle is what returned by enqueue().
Clear the queue.
Try to dequeue manually. In most cases, the queue will handle all the dequeue works itself.

The deferred queue

Here's a nice reading by Nicholas C. Zakas
The basic idea of the deferred option of $queueFactory is to utilize setImmediate() API to ease the browser freezing problems which we sometimes encountered when dealing with heavy-load tasks. Though it's not implemented on every browser, if you kindly provide a polyfill, we're still good.
In the condition that ngQueue can't find the setImmeidate() API, it'll use $timeout of AngularJS instead.
Note: Special thanks to Chih-Hsuan Fan
Disclaimer: The blog is created to share angular directives information to geek, curious Angular Developers.