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 displayResult(){
	var x=document.getElementById("pwd").maxLength;
	alert(x);
}
</script>
</head>
<body>

<form>
密码: <input type="password" id="pwd" maxlength="8">
</form>
<button type="button" onclick="displayResult()">显示允许输入的最多字符数</button>

</body>
</html>

源代码

动行结果