logger.js

gistfile1.js

(function () {

  "use strict";

  var Logger = this.Logger = function ($el) {
    this.$logger = $el;
    this.timers = {};
  }

  Logger.prototype.stop = function (label) {
    this.timers[label].end = new Date().getTime();
    this.timers[label].time = this.timers[label].end - this.timers[label].start;
    this.log(label +  ': ' + this.timers[label].time + 'ms');
  }

  Logger.prototype.start = function (label) {
    this.timers[label] = {};
    this.timers[label].start = new Date().getTime();
  }

  Logger.prototype.clear = function () {
    this.timers = {};
    this.$logger.html('');
  }

  Logger.prototype.log = function (message) {
    this.$logger.append('<p>' + message + '</p>');
  }

}).call(this);

// usage

var logger = new Logger($('#logger'));

logger.start('label1');
logger.stop('label1'); // prints time taken