Timer on Deferreds

timer-on-deferreds.js

//Timer on Deferreds
(function (){
	var top = this;	
	var defaults = {
		granularity : 500,
		name : 'default'
	};

	this.Timer = function(timeout, options){
		var o = $.extend({}, defaults, options),
			granularity = o.granularity,
			name = o.name;
	
		var coreFunctionality, timeoutFuncRef, tickRef;
		
		var timeStarted = new Date() - 0, 
			timeElapsed = 0, 
			lastKnownTime = timeStarted,
			isRunning = false;
			
		return $.Deferred(function(def){
			coreFunctionality = {
				pause: function(){
					if (!isRunning)
						return;
						
					var time = new Date() - 0, elapsed = time - lastKnownTime;
					timeElapsed += elapsed;
					lastKnownTime = time;
					
					top.clearTimeout(timeoutFuncRef);
					timeoutFuncRef = null;
					isRunning = false;
				},
				resume: function(){
					if (isRunning)
						return;
					lastKnownTime = new Date() - 0;
					timeoutFuncRef = window.setTimeout(def.resolve, timeout - timeElapsed);
					isRunning = true;
				},
				stop: function(){
					def.resolve();
					cleanup();
				},
			};
			timeoutFuncRef = window.setTimeout(def.resolve, timeout - timeElapsed);
			tickRef = window.setInterval(function(){
				if (!isRunning)
					return;
				var time = new Date() - 0, elapsed = time - lastKnownTime;
					timeElapsed += elapsed;
					lastKnownTime = time;
				def.notify({
					name: name,
					total: timeout,
					elapsed: timeElapsed
				});						
			}, granularity);
			isRunning = true;
		}).promise(coreFunctionality);
		
		function cleanup(){
			top.clearTimeout(timeoutFuncRef);
			timeoutFuncRef = null;
			
			top.clearInterval(tickRef);
			tickRef = null;
			
			isRunning = false;
		}
	};

})();