JS - 兼容的事件助手

(function () {
  // 兼容的事件助手
  window.CompatibleEventHelper = {
    addEventListener: function (elem, type, cb) {
      if (elem.addEventListener) {
        elem.addEventListener(type, cb, false);
      }
      else if (elem.attachEvent) {
        elem.attachEvent('on' + type, cb);
      }
      else {
        elem['on' + type] = cb;
      }
    },
    removeEventListener: function (elem, type, cb) {
      if (elem.removeEventListener) {
        elem.removeEventListener(type, cb, false);
      }
      else if (elem.detachEvent) {
        elem.detachEvent('on' + type, cb);
      }
      else {
        elem['on' + type] = null;
      }
    },
    getEvent: function (event) {
      return event || window.event;
    },
    getTarget: function (event) {
      event = this.getEvent(event);
      return event.target || event.srcElement;
    },
    preventDefault: function (event) {
      event = this.getEvent(event);
      if (event.preventDefault) {
        event.preventDefault();
      }
      else {
        event.returnValue = false;
      }
    },
    stopPropagation: function (event) {
      event = this.getEvent(event);
      if (event.stopPropagation) {
        event.stopPropagation();
      }
      else {
        event.cancelBubble = true;
      }
    }
  };
})();

/*
范例：

html:
<div id="box">box</div>

js:
var box = document.getElementById('box');
CompatibleEventHelper.addEventListener(box, 'click', function (event) {
  // do something...
});

*/