var self = document.getElementsByTagName("a");
for(var i=0;i<self.length;i++){
self[i].onclick = (function(i){
return function(){
alert(i);
}
})(i)
}
<a href="javascript:;">我是老大</a>
<a href="javascript:;">我是老二</a>
<a href="javascript:;">我是老三</a>
var self = document.getElementsByTagName("a");
for(var i=0;i<self.length;i++){
self[i].onclick = (function(i){
return function(){
alert(i);
}
})(i)
}
<a href="javascript:;">我是老大</a>
<a href="javascript:;">我是老二</a>
<a href="javascript:;">我是老三</a>