JavaScript event兼容性

Event兼容性代码,按照W3C标准兼容:

var fixEvent = function(e){
    e =  e || window.event;
	if(!e.preventDefault){
	  e.preventDefault = function(){
	    event.returnValue = false;
	  };
	}
	if(!e.stopPropagation){
	  e.stopPropagation = function(){
	     event.cancelBubble = true;
	  };
	}
	if(e.pageX === undefined && e.pageY === undefined){
	  var doc =document.documentElement || document.body;
	  e.pageX = e.clientX + doc.scrollLeft - doc.clientLeft;
	  e.pageY = e.clientY + doc.scrollTop - doc.clientTop;
	}
	if(!e.target){
	  e.target = e.srcElement;
	}
	return e;
  };