我希望用户能够从多个选择选项中最多只选择三个。到目前为止,我已经尝试了以下代码:
<select id="userRequest_activity" required name="activity[]" class="multiselect form-control" multiple="multiple">
<option value="2">Bungee Jumping</option>
<option value="3">Camping</option>
<option value="5">Mountain Biking</option>
<option value="6">Rappelling</option>
<option value="7">Rock Climbing / Bouldering</option>
<option value="8">Skiing</option>
<option value="10">Wild Life (Safari)</option>
<option value="11">Canoeing & Kayaking</option>
<option value="12">Rafting</option>
<option value="13">Sailing</option>
<option value="14">Scuba Diving</option>
<option value="15">Snorkeling</option>
<option value="16">Surfing</option>
<option value="18">Hang Gliding</option>
<option value="19">Hot-air Ballooning</option>
<option value="20">Micro-light Aircrafts</option>
<option value="21">Paragliding</option>
<option value="22">Paramotoring</option>
<option value="23">Parasailing</option>
<option value="24">Skydiving / Parachuting</option>
<option value="25">Zip-line / Flying Fox</option>
<option value="26">Caving</option>
<option value="27">Cycling</option>
<option value="28">Fishing & Angling</option>
<option value="29">Motorbike trips</option>
<option value="30">Nature Walks</option>
<option value="31">Road Trips</option>
<option value="32">Zorbing</option>
<option value="33">Trekking Hiking and Mountaineering</option>
<option value="34">Backpacking</option>
<option value="61">Water</option>
</select>
javascript代码:
<script type="text/javascript">
$("select").change(function() {
if ($("select option:selected").length > 3) {
$(this).removeAttr("selected");
alert('You can select upto 3 options only');
}
});
</script>
当选择的选项超过3个时,此代码会显示警告框,但仍允许选择第4、5、6等选项并显示警告框。如何验证这一点?