html - 验证到

您可以使用以下代码片段：

<form>
        <label>Prefered Time</label><span id="time-info" class="info"></span><br />
        <select class="input-field" name="time" id="time" required>
            <option value="">None</option>
            <option value="Morning">Morning: 9am - 12pm</option>
            <option value="Afternoon">Afternoon: 12pm - 5pm</option>
            <option value="Evening">Evening: 5pm - 9pm</option>                   
        </select>
        <br><br>
        <input type="submit" value="Submit">
 </form>

单击提交按钮将触发验证。使用以下“必需”类属性。

<select id="select" class="required">