Run Loop Metrics Bookmarklet

gistfile1.js

javascript:(function(){
  
  var getTimestamp = function() { return new Date().getTime(); };
  if (window.performance.now) {
    getTimestamp = function() { return window.performance.now(); };
  } else if (window.performance.webkitNow) {
    getTimestamp = function() { return window.performance.webkitNow(); };
  }

  var startTime, endTime, loopCount = 0;
  var onBegin = Ember.run.backburner.options.onBegin;
  var wrappedOnBegin = function(current) {
    loopCount++;
    console.log('run loop: #' + loopCount);
    startTime = getTimestamp();
    onBegin();
  };
  Ember.run.backburner.options.onBegin = wrappedOnBegin;

  var onEnd = Ember.run.backburner.options.onEnd;
  var wrappedOnEnd = function(current) {
    onEnd();
    endTime = getTimestamp();
    console.log('loop duration: ' + (endTime - startTime) + 'ms');
  };
  Ember.run.backburner.options.onEnd = wrappedOnEnd;

})();