<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>for</title>
</head>
<body>
<button>1</button>
<button>2</button>
<button>3</button>
<script type="text/javascript">
var btns = document.getElementsByTagName('button');
for (var i = 0; i < 3; i++) {
num(i);
}
function num(i){
btns[i].onclick = function () {
alert(i+1 )
}
}
//在此处修改代码
</script>
</body>
</html>
