Javascript“多重选择”选择框验证？
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Javascript "MULTIPLE Selection" Select box validation?
提问by OM The Eternity
I Have a Multiple selection select box. I need it to be validated using javascript, so that it should prompt to select atleast one value.
我有一个多选选择框。我需要使用 javascript 对其进行验证，以便它应提示选择至少一个值。
Below is the multiple select box I Have.
下面是我有的多选框。
<select name="usrgrp[]" multiple="multiple" size="3">
<option value="11">abc</option>
<option value="12">def</option>
<option value="13">ghi</option>
</select>
Please help me to write the validation javascript for this select box.
请帮我为这个选择框编写验证javascript。
回答by RoToRa
if (referenceToForm.elements["usrgrp[]"].selectedIndex == -1) {
alert("Please select an item.");
}
回答by Yoesoff
the easiest way is use ! :
最简单的方法是使用！：
if (!$('select').val())
{
//fail
}
回答by McStretch
I would start with the Validationdocs. If you find the need to validate more than just that field (perhaps you're building a form?), then using the Validation pluggin will help you much more than hacking together individual rules.
我将从验证文档开始。如果您发现需要验证的不仅仅是该字段（也许您正在构建一个表单？），那么使用验证插件对您的帮助不仅仅是将单个规则组合在一起。
Give it a shot, it's well written and contains many examples.
试一试，它写得很好，包含很多例子。
