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>
</head>
<body>

<form action="form_action.asp.html">
姓名: <input type="text" id="myText" name="fname" required>
<input type="submit">
</form>
<p>点击 "点我" 按钮查看文本域是否是表单提交的必填部分。</p>
<button onclick="myFunction()">点我</button>
<p id="demo"></p>
<script>
function myFunction() {
    var x = document.getElementById("myText").required;
    document.getElementById("demo").innerHTML = x;
}
</script>

</body>
</html>
源代码

动行结果
