The purpose of the class is to execute all the registered functions asynchronously and then, once all of them are finished, It should execute the defined callback function.

(function() {
    function Batch(functions, completionHandler) {
        this._functions = functions;
        this._completionHandler = completionHandler; 
    }
    Batch.prototype.execute = function execute() {
        var i;
        var functions = this._functions;
        var length = this._remaining = functions.length;
        this._results = [];
        for (i = 0; i < length; i += 1) {
            functions[i](this);
        }
    };
    Batch.prototype.done = function done(result) {
        this._remaining -= 1;
        console.log(['Function set a timer of ', result, 'ms'].join(''));
        if (typeof result !== 'undefined') {
            this._results.push(result);
        }
        if (this._remaining === 0 && _lock === false) {
            this._completionHandler(this._results);
            _lock = true;
        }
    };
    this.Batch = Batch;
}.call(this));
var _lock = false;
var batchFunctions = [];
var min = 500;
var max = 1500;
var timeout = 1000; //set time out for callback
for (var i = 0; i < 10; i += 1) {
    batchFunctions.push(function (batch) {
        var time = Math.floor(Math.random() * (max - min) + min);
        //Some ajax call instead of setTimeout function...
        setTimeout(function () {
            batch.done(time);
            //console.log(i +' '+time);
        }, time);
    });
}
var callback_f = function (results) {
    console.log('callback Executed.....');
}
var timerBatch = new Batch(batchFunctions, callback_f);

timerBatch.execute();
setTimeout(function () {
    if(_lock === false){
        console.log('Timed Out .....');
        _lock = true;
        callback_f();
    }
}, timeout);