创建 跨浏览器兼容事件

//事件兼容代码
var EventUtil = {
addHandler: function(element, type, handler) {

  },

  getEvent: function(event) {
    return event ? event : window.event;
  },

  getTarget: function(event) {
    return event.target || event.srcElement;
  },

  preventDefault: function(event) {
    if (event.preventDefault) {
      event.preventDefault();
    } else {
      event.returnValue = false;
    }
  },

  removeHandler: function(element, type, handler) {

  },

  stopPropagation: function(event) {
    if (event.stopPropagation) {
      event.stopPropagation();
    } else {
      event.cancelBubble = true;
    }
  }
}

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在《高程3》中的例子