function_queue.js

/*

 function queue

  based on

  https://stackoverflow.com/questions/17528749/semaphore-like-queue-in-javascript/17528961#17528961

*/

var Queue = (function(){

    function Queue(autorun) {
        if (typeof autorun !== "undefined") {
            this.autorun = autorun;
        }
        this.queue = []; //initialize the queue
    }
 
    Queue.prototype.autorun = true;
    Queue.prototype.running = false;
    Queue.prototype.queue = [];

    Queue.prototype.add = function(callback) {
        var _this = this;
        //add callback to the queue
        this.queue.push(function() {
            var finished = callback();
            if (typeof finished === "undefined" || finished) {
                //  if callback returns `false`, then you have to 
                //  call `next` somewhere in the callback
                _this.dequeue();
            }
        });
        if (this.autorun && !this.running) {
            // if nothing is running, then start the engines!
            this.dequeue();
        }
        return this; // for chaining fun!
    };

    Queue.prototype.dequeue = function() {
        this.running = false;
        //get the first element off the queue
        var shift = this.queue.shift();
        if (shift) {
            this.running = true;
            shift();
        }
        return shift;
    };

    Queue.prototype.next = Queue.prototype.dequeue;
    return Queue;
})();

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

var fqueue = new Queue();

function say(msg,cb){
    console.log('say:',msg);
    cb();
}

function shout(msg,cb){
    console.log('shout:',msg);
}

function wisper(msg,cb){
    console.log('wisper:',msg); 
}

function cb(){
    console.log('done');
}

fqueue.add(function(){say('hello',cb);});

setTimeout(function(){
    fqueue.add(function(){shout('Hey');});
},1000);

setTimeout(function(){
    fqueue.add(function(){wisper('can you hear me?');});
},2000);

setTimeout(function(){
    for (i=0;i<50;i++){
        fqueue.add(function(){say('job id='+ i.toString(),cb);});
    }
},3000);