多个选择限制选择的数量 [英] Multiple Select limit number of selection
本文介绍了多个选择限制选择的数量的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我希望用户从多个选择选项中选择最多只有三个选项。到目前为止，我尝试了以下代码：
< select id =userRequest_activityrequired name =activity []class = multiselect form-controlmultiple =multiple>
< option value =2> Bungee Jumping< / option>
< option value =3>露营< / option>
< option value =5> Mountain Biking< / option>
< option value =6> Rappelling< / option>
< option value =7>攀岩/抱石< / option>
< option value =8> Skiing< / option>
< option value =10> Wild Life（Safari）< / option>
< option value =11>皮划艇& amp; amp; amp;皮划艇< /选项>
< option value =12>漂流< / option>
< option value =13>航行< / option>
< option value =14> Scuba Diving< / option>
< option value =15>浮潜< / option>
< option value =16> Surfing< / option>
< option value =18>悬挂滑翔< / option>
< option value =19> Hot-air Ballooning< / option>
< option value =20> Micro-light Aircrafts< / option>
< option value =21>滑翔伞< / option>
< option value =22> Paramotoring< / option>
< option value =23> Parasailing< / option>
< option value =24>跳伞/跳伞< / option>
< option value =25> Zip-line / Flying Fox< / option>
< option value =26>放气< /选项>
< option value =27>单车< / option>
< option value =28>钓鱼& amp; amp;钓鱼< /选项>
< option value =29>摩托车行程< / option>
< option value =30> Nature Walks< / option>
< option value =31>公路旅程< / option>
< option value =32> Zorbing< / option>
< option value =33>徒步登山&登山< / option>
< option value =34>背包< / option>
< option value =61>水< / option>
< / select>
javascript代码：
< script type =text / javascript>
$（select）。change（function（）{
if（$（select option：selected）。length> 3）{
$（this）.removeAttr selected）;
alert（'您最多可以选择3个选项'）;
}
}）;
< / script>
此代码显示警告框，当选择多于3个选项时仍然允许访问选择第4，第5，第6等等选择与警报框出现。如何验证这一点？
解决方案
试试这个...
检查长度并在达到最大值后取消选择
< select id =userRequest_activityrequired name =activity []class = multiselect form-controlmultiple =multiple>
< option value =2> Bungee Jumping< / option>
< option value =3>露营< / option>
< option value =5> Mountain Biking< / option>
< option value =6> Rappelling< / option>
< option value =7>攀岩/抱石< / option>
< option value =8> Skiing< / option>
< option value =10> Wild Life（Safari）< / option>
< option value =11>皮划艇& amp; amp; amp;皮划艇< /选项>
< option value =12>漂流< / option>
< option value =13>航行< / option>
< option value =14> Scuba Diving< / option>
< option value =15>浮潜< / option>
< option value =16> Surfing< / option>
< option value =18>悬挂滑翔< / option>
< option value =19> Hot-air Ballooning< / option>
< option value =20> Micro-light Aircrafts< / option>
< option value =21>滑翔伞< / option>
< option value =22> Paramotoring< / option>
< option value =23> Parasailing< / option>
< option value =24>跳伞/跳伞< / option>
< option value =25> Zip-line / Flying Fox< / option>
< option value =26>放气< /选项>
< option value =27>单车< / option>
< option value =28>钓鱼& amp; amp;钓鱼< /选项>
< option value =29>摩托车行程< / option>
< option value =30> Nature Walks< / option>
< option value =31>公路旅程< / option>
< option value =32> Zorbing< / option>
< option value =33>徒步登山&登山< / option>
< option value =34>背包< / option>
< option value =61>水< / option>
< / select>
< script type =text / javascript>
$ b $（文档）.ready（函数（）{
var last_valid_selection = null;
$（'＃userRequest_activity' ）.change（function（event）{
if（$（this）.val（）。length> 3）{
$（this）.val（last_valid_selection ）;
} else {
last_valid_selection = $（this）.val（）;
}
}）;
}）;
< / script>
DEMO： http://jsfiddle.net/9c3sevuv/
I want user to select maximum of only three options from multiple select options. I tried this code so far:
<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>
The javascript code:
<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>
This code shows the alert box when selected more than 3 options but still allow access to select the 4th, 5th, 6th and so on selections with the alert box appearing. How to validate this?
解决方案
Try this...
Check length and deselect after reach maximum select
<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>
<script type="text/javascript">
$(document).ready(function() {
var last_valid_selection = null;
$('#userRequest_activity').change(function(event) {
if ($(this).val().length > 3) {
$(this).val(last_valid_selection);
} else {
last_valid_selection = $(this).val();
}
});
});
</script>
DEMO:http://jsfiddle.net/9c3sevuv/
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