在线运行代码 - 菜鸟教程

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>菜鸟教程(cainiaoplay.com)</title>
<script>
function myFunction(){
	document.getElementById("email").select();
}
</script>
</head>
<body>

<form>
Email: <input type="text" id="email" value="someone@example.com">
</form>
<button type="button" onclick="myFunction()">选取内容</button>

</body>
</html>

源代码

动行结果