jquery 验证插件上的自定义验证，需要计算多选中的元素
我有一个多重选择，我需要强制用户选择最多两个选项，仅此而已。
我正在尝试这个：
jQuery.validator.addMethod("morethantwo",
function(value, element) {
var foo = [];
$(element+' :selected').each(function(i, selected){
foo[i] = $(selected).text();
alert(foo[i]);
});
return true;
},"Max two options."
);
问题是我收到一个：
uncaught exception: Syntax error, unrecognized expression: [object HTMLSelectElement]
错误。虽然如果我这样做：
$(element).each(function(i, selected){
foo[i] = $(selected).text();
alert(foo[i]);
});
它有效，但我得到了选择中的所有选项。这是为什么？这是正确的路吗？有没有更好的方法来进行此类检查？
非常感谢！
I have a multiple select, and I need to force the user to choose maximum two options, nothing more.
I'm trying this:
jQuery.validator.addMethod("morethantwo",
function(value, element) {
var foo = [];
$(element+' :selected').each(function(i, selected){
foo[i] = $(selected).text();
alert(foo[i]);
});
return true;
},"Max two options."
);
The problem is that I get a:
uncaught exception: Syntax error, unrecognized expression: [object HTMLSelectElement]
error. While if I do this:
$(element).each(function(i, selected){
foo[i] = $(selected).text();
alert(foo[i]);
});
It works but I get all the options in the select. Why is that? Is this the correct road to walk? Are there better ways to do this kind of check?
Thank you very much!
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要回答它损坏的原因，
element是一个 DOM 元素，而不是字符串，因此在该代码中，您尝试执行DOMElement+string...但事实并非如此。不工作:)而是包装 DOM 元素并使用.find()或.children()获取选项。知道它为何损坏后，您可以像这样编写规则来检查所选选项：
在此处查看上述代码的演示
如果您严格处理
因为
.val()返回一个数组。To answer the why it's breaking,
elementis a DOM element, not a string, so in that code you're trying to doDOMElement+string...which doesn't work :) Instead wrap the DOM element and use.find()or.children()to get the options.Knowing why it broke, you can write your rule like this to check the selected options:
Check here for a demo of the above code
If you're strictly dealing with a
<select multiple>you could do this as well:Since
.val()returns an array in that case.