''必需'功能似乎不适用于返回确认

Question

当我提交不完整的数据时，为什么我的要求不会触发？这是我的代码如下：

<form class="form-adminpage" method="post" action="admin.php">
                <input type="text" name="project_title" placeholder="Project Title" required /><br>
                <input type="text" name="city" placeholder="City" required /><br>
                <input type="text" name="province" placeholder="Province" required /><br>
                <input type="text" name="cost" placeholder="Cost" required /><br>
                <input type="Submit" name="button" value="Enter" onclick="return confirm('Are you sure you want to add the following data?');">
            </form>

Answer 1

onclick将首先触发。如果要首先显示HTML 5验证，可以在表单的onsubmit事件中添加警报

<form class="form-adminpage" method="post" action="admin.php" onsubmit="return confirm('Are you sure you want to add the following data?');">
    <input type="text" name="project_title" placeholder="Project Title" required="true" /><br>
    <input type="text" name="city" placeholder="City" required /><br>
    <input type="text" name="province" placeholder="Province" required /><br>
    <input type="text" name="cost" placeholder="Cost" required /><br>
    <input type="Submit" name="button" value="Enter" >
</form>