StopWatch time measurement class for profiling javascript apps.

debug.js

/*
	StopWatch. A time profiler.
	Use:
		var stopwatch = StopWatch("My Stop Watch");
		// ... do something here
		stopwatch.lap("step1");
		// ... do something more
		stopwatch.lap("step2").print();
		// Console log at this point:
		// [SW "My Stop Watch"]: step1 = 12 ms,	step2 = 20 ms
*/
function StopWatch(name) {
	this._name = name;
	this._laps = new Array();
	this._start = new Date().getTime();
}

StopWatch.prototype.lap = function(name) {
	var time = new Date().getTime();
	if (!name) name = '' + this._laps.length;
	this._laps.push({'name' : name, 'timestamp' : time});
	return this;
}

StopWatch.prototype.print = function() {
	if (!console) return;
	
	var lastTimestamp = this._start;
	var text = '[SW "' + this._name + '"]:';
	for (var i =0; i < this._laps.length; i++) {
		var lap = this._laps[i];
		text += ' ' + lap['name'] + ' = ' + (lap['timestamp']-lastTimestamp) + ' ms';
		if (i+1 < this._laps.length) text += ',\t';
		lastTimestamp = lap['timestamp'];
	}

	console.log(text);
	return this;
}