App下載
實(shí)例代碼( Tip: 登錄后體驗(yàn)更佳 )
<!DOCTYPE html>
<html>
<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>
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