JavaScript事件模型详解：冒泡、捕获与兼容处理

function(event){ 
  //event 是作为DOM标准的参数传入处理函数 
 event = event ?event : window.event; 
} 

var target =event.srcElement ? event.srcElement : event.target ;

element.attachEvent('onclick',observer); //注册监听器
element.detachEvent('onclick',observer) //移除监听器

element.addEventListener('click',observer,useCapture) 
element.removeEventListener('click',observer,useCapture)

function someHandler(event){ 
  event = event || window.event; 
  if(event.stopPropagation) //DOM标准 
  event.stopPropagation(); 
  else 
  event.cancelBubble = true; //IE标准 
} 

function someHandler(event){ 
  event = event || window.event; 
  if(event.preventDefault) //DOM标准 
  event. preventDefault (); 
  else 
  event.returnValue = true; //IE标准 
}