event相关函数跨浏览器汇总

var EventUtil = {
  addHandler: function (element, type, handler) {
    if (element.addEventListener) {
      element.addEventListener(type, handler, false);
    } else if (element.attachEvent) {
      element.attachEvent("on" + type, handler);
    } else {
      element["on" + type] = handler;
    }
  },
  removeHandler: function (element, type, handler) {
    if (element.removeEventListener) {
      element.removeEventListener(type, handler, false);
    } else if (element.detachEvent) {
      element.detachEvent("on" + type, handler);
    } else {
      element["on" + type] = null;
    }
  },
  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;
    }
  },
  stopPropagation: function (event) {
    if (event.stopPropagation) {
      event.stopPropagation();
    } else {
      event.cancelBubble = true;
    }
  },
  getRelatedTarget: function (event) {
    if (event.relatedTarget) {
      return event.relatedTarget;
    } else if (event.toElement) {
      return event.toElement;
    } else if (event.fromElement) {
      return event.fromElement;
    } else {
      return null;
    }
  },
  // 检测鼠标按下的是左-0/中-1/右-2键
  getButton: function (event) {
    if (document.implementation.hasFeature("MouseEvents", "2.0")) {
      return event.button;
    } else {
      switch (event.button) {
        case 0:
        case 1:
        case 3:
        case 5:
        case 7:
          return 0;
        case 2:
        case 6:
          return 2;
        case 4:
          return 1;
      }
    }
  },
  // 获取按键code，或使用event.key || event.keyIdentifier获取键值
  getCharCode: function (event) {
    if (typeof event.charCode == "number") {
      return event.charCode;
    } else {
      return event.keyCode;
    }
  },
};