<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
</head>
<body>
<p>1</p>
<p>2</p>
<p>3</p>
<script>
var oP=document.getElementsByTagName("p")
for(var i=0;i<oP.length;i++){
oP[i].index=i
oP[i].onclick=function(){
console.log(i) //3 【for里面套函数，i为跳出循环的数】
alert(this.index)
}
}
</script>
</body>
</html>