DOM-events-counter

DOMOperationCounter = (function() {
  var self;
  if(!window.__DOMOperationCounterCallback) {
      self = window.__DOMOperationCounterCallback = function(event) {
      self.counter++;
      self.details[event.type] = self.details[event.type] ? self.details[event.type] + 1 : 1; 
    }
    self.counter = 0;
    self.toggleState = false;
    self.details = {};
  } else {
 	  self = window.__DOMOperationCounterCallback;
  }
  return function(start) {
    var events = 'DOMSubtreeModified DOMNodeInserted DOMNodeRemoved DOMNodeRemovedFromDocument DOMNodeInsertedIntoDocument DOMAttrModified DOMCharacterDataModified';
    events = events.split(' ');
    if(start === undefined) {
      start = self.toggleState = !self.toggleState;
    }
    
    if(start) {
      self.counter = 0;
      events.forEach(function(eventName) {
        document.addEventListener(eventName, window.__DOMOperationCounterCallback, true);
      });
    } else {
      console.log('Captured DOM events:', self.counter);
      console.log('DOM events byt type:', self.details);

      events.forEach(function(eventName) {
        document.removeEventListener(eventName, window.__DOMOperationCounterCallback, true);
      });
    }
    return 'Trigger DOMOperationCounter again to see result.';
  };
})();

DOMOperationCounter();