是否可以为下拉菜单设置错误消息？
在第一页上，我有一个下拉菜单，用户可以选择任意组合，然后点击提交。
在第二页上，我有相同的精确下拉菜单，如果用户没有选择相同的组合，则会显示一些错误。
<select id="men" class="select_class1" name="subselector" style="display:none" >
<option value="">Choose an item</option>
<option value="tsm">T-Shirt</option>
<option value="lsm">long sleeve</option>
<option value="tankm">Tank Top</option>
</select>
<select id="color" class="select_class1" name="subselector" style="display:none" >
<option value="">Choose an item</option>
<option value="blue">blue</option>
<option value="red">red</option>
<option value="black">black</option>
</select>
答案 0 :(得分：0)
是。您可以通过 PHP 和 JQUERY
的组合来实现这一目标让我们说这是你的第一页
secondPage.php然后这将是您的<?php
$subselector = $_POST['subselector'];
?>
<form action="anotherPage.php" method="post">
<select id="men" class="select_class1" name="subselector">
<option value="">Choose an Item</option>
<option value="tsm">T-Shirt</option>
<option value="lsm">Long Sleeve</option>
<option value="tankm">Tank Top</option>
</select>
<input type="submit" value="submit" />
</form>
<!-- Now using jQuery to prevent the form from submitting if only the previous selected value doesn't correspond with the present selected value -->
<!-- don't forget to include your jQuery library here -->
<script>
$('form').submit(function(e){
prevSelVal = "<?php echo $subselector; ?>";
presentVal = $('select').val();
if(prevSelVal !== presentVal){
e.preventDefault();
alert('Your Previous Selected Value must Correspond With Your Present Selected Value');
}
});
</script>
var c = document.getElementById('test'), ctx = c.getContext('2d');
ctx.save();
ctx.fillStyle = "rgba(0,0,255,0.5)";
ctx.beginPath();
ctx.moveTo(25, 0);
ctx.lineTo(50, 50);
ctx.lineTo(0, 50);
ctx.lineTo(25, 0);
ctx.fill();
ctx.fillStyle = "rgba(255,0,0,0.5)";
ctx.beginPath();
ctx.moveTo(50, 0);
ctx.lineTo(75, 50);
ctx.lineTo(25, 50);
ctx.lineTo(50, 0);
ctx.clip();
ctx.clearRect(0, 0, 100, 100);
ctx.fill();
ctx.restore();