菜鸟教程在线编辑器

AI 编程工具
 
                <!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>菜鸟教程(runoob.com)</title>
</head>
<body>

<form action="form-action.php">
搜索: <input type="search" id="mySearch" name="filter">
<input type="submit" value="提交">
</form>
<p>点击 "点我" 按钮设置搜索字段 required 属性。</p>
<p><strong>提示:</strong> 在点击 “点我” 按钮前后点击  "提交" 按钮查看效果</p>
<button onclick="myFunction()">点我</button>
<p id="demo"></p>
<script>
function myFunction() {
    document.getElementById("mySearch").required = true;
    document.getElementById("demo").innerHTML = " required 属性已设置。表单提交前搜索字段为必填字段。 ";
}
</script>

</body>
</html>
              