JavaScript事件委托实现原理与代码示例

var addEvent = function (elem, eventType, func) {
 if ( elem.addEventListener )
  addEvent = function (elem, eventType, func) {
   elem.addEventListener(eventType, func, false);
  };
 else if ( elem.attachEvent )
  addEvent = function (elem, eventType, func) {
   elem.attachEvent('on' + eventType, func);
  };
 addEvent(elem, eventType, func);
};
var delegateEvent = function (elem, childElems, eventType, func, args) {
 addEvent(elem, eventType, function (e) {
  var evt = e || window.event;
  var elem = evt.target || evt.srcElement;
  if ( elem.nodeName.toLowerCase() == childElems.toLowerCase() ) {
   func(elem, args);
  }
 });
};