A simple stats display

stats.js

(function() {
	var Stats = function() {
		var d = document.createElement("div");
		d.setAttribute("style","color:#fff;font-size:10px;position:absolute;top:2px;left:2px;width:80;height:30px;padding:5px;z-index:1000;background:rgba(0,0,0,0.85);");
		document.getElementsByTagName("body")[0].appendChild(d);	
		this.d = d;
		this.stats = {};
		this.measurements = {};
	};

	Stats.prototype.add = function(stat,options) {
		var options = options || {};
		if(!this.stats[stat]) {
			this.stats[stat] = options;
			this.measurements[stat] = [];
		};
	}

	Stats.prototype.measurement = function(stat, value) {
		if(this.measurements[stat]) {
			if(this.measurements[stat].length >= 16) {
				this.measurements[stat].shift();
			}
			this.measurements[stat].push(value);
		};
	};

	Stats.prototype.loop = function() {
		this.draw();	
	}
	Stats.prototype.draw = function() {
		this.d.innerHTML = "";
				for(var i in this.stats) {
					switch(this.stats[i].mode) {
						case 'bars':
							this.d.innerHTML += this.stats[i].label+": "+this.getBars(i);+"<br />";
							break;
						default:
							this.d.innerHTML += this.stats[i].label+": "+this.measurements[i][this.measurements[i].length-1];+"<br />";
					}
				}

	}
	Stats.prototype.getBars = function(stat) {
		var html = "";
		if(this.stats[stat]) {
			html = "<div style='position:relative;height:20px;width:80px;'>";
			var s = this.stats[stat];
			var av = 0;
			var min = 1000000;
			var max = 0;
			for(var i in s) {
				av += s[i];
				max = (s[i] > max ? s[i] : max);
				min = (s[i] < max ? s[i] : max);
			}
			av /= s.length;
			var d = 20; //max-min-1;

			for(var i in s) {
				var l = i*5;
				//var h = (s[i]-min+1)*d;
				var h = (s[i]/max)*d;
				html += "<div style='position:absolute;background:rgba(255,255,255,0.85);bottom:0;width:5px;left:"+l+"px;height:"+h+"px;'></div>";
			}
			html += "</div>";
		}

		return html;
	}
	Stats.prototype.start = function() {
		if(!this.running) {
			var self = this;
			this.timer = setInterval(function() {
				self.loop();
			},1000/24);	
			this.running = true;
		}
	}
	Stats.prototype.stop = function() {
		clearInterval(this.timer);
		this.running = false;
	}

	window.addEventListener('load', function() { 
		window.stats = new Stats();
	});

})();