<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<button>按钮1</button>
<button>按钮2</button>
<button>按钮3</button>
<button>按钮4</button>
<button>按钮5</button>
</body>
<script>
let btns = document.getElementsByTagName(‘button‘)
for (var i = 0; i < btns.length; i++) {
btns[i].onclick = function () {
alert(‘点击了‘ + i + ‘个‘)
}
}
for (var i = 0; i < btns.length; i++) {
(function (i) {
btns[i].onclick = function () {
alert(‘点击了‘ + i + ‘个‘)
}
})(i)
}
for (let i = 0; i < btns.length; i++) {
btns[i].onclick = function () {
alert(‘点击了‘ + i + ‘个‘)
}
}
</script>
</html>