jQuery 选择器问题
<input type="radio" id="rad1" name="group" value="one">First Option</input><br>
<input type="radio" id="rad2" name="group" value="two">Second Option</input><br>
<input type="radio" id="rad3" name="group" value="three">Third Option</input><br>
<br>
<input type="radio" id="rad7" name="group2" value="one">First Option</input><br>
<input type="radio" id="rad8" name="group2" value="two">Second Option</input><br>
<input type="radio" id="rad9" name="group2" value="three">Third Option</input><br>
以下陈述是true
$('[value="one"]').length == 2
$('[name="group2"]').length == 3
那么怎么会..
$('[value="one"]',$('[name="group2"]')).length == 0
？
我本以为这应该有效地在所有具有 name==group2 的元素中查找具有 value=="one" 即 1 的元素。为什么情况并非如此？
<input type="radio" id="rad1" name="group" value="one">First Option</input><br>
<input type="radio" id="rad2" name="group" value="two">Second Option</input><br>
<input type="radio" id="rad3" name="group" value="three">Third Option</input><br>
<br>
<input type="radio" id="rad7" name="group2" value="one">First Option</input><br>
<input type="radio" id="rad8" name="group2" value="two">Second Option</input><br>
<input type="radio" id="rad9" name="group2" value="three">Third Option</input><br>
The following statements are true
$('[value="one"]').length == 2
$('[name="group2"]').length == 3
So how come..
$('[value="one"]',$('[name="group2"]')).length == 0
?
I would have thought that this should effectively look within all elements with name==group2 for elements with value=="one" ie 1. Why is this not the case?
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此选择器使用作用域/上下文的第二个参数：
尝试查找具有
[value="one"]且 源自 具有[name=" 的元素组2"]。这意味着您最终会向下查找 DOM 中至少两层不同的元素。在您的情况下，您的单选按钮具有这两个属性，因此您想要附加两个属性选择器（我添加
input只是为了节省 jQuery 的一些工作）：This selector, using the second argument for scope/context:
Attempts to find elements with
[value="one"]that descend from elements with[name="group2"]. That means you end up looking down at least two levels of different elements in the DOM.In your case, your radio buttons have both attributes, so you want to attach both attribute selectors instead (I add
inputjust to save jQuery some work):我认为您想要的是：
这选择具有
name属性且值为group2和value属性的元素值一。$(selector, element)是不同的。它将找到与selector匹配的element的所有后代。请参阅文档。I think what you want is:
This selects elements that have a
nameattribute with valuegroup2andvalueattribute with valueone.$(selector, element)is something different. It will find all descendants ofelementwhich matchselector. See the documentation.您必须使用一个字符串，以逗号分隔。顺便说一句，编写像
[anything=foobar]这样的选择器是不好的做法。这是通用选择器(*)的隐式用法，它将查询标记中的所有元素。这将查询两个选择器并将结果添加到一个包装集中。如果您想查询拥有这两个属性的节点，请将其连接起来，如下所示：
You have to use one string, comma separated. BTW it's bad practice to write a selector like
[anything=foobar]. That is an implicit usage of the universal selector(*) which would query all elements in your markup.This would query both selectors and add the results together in a wrapped set. If you want query for nodes which own both attributes, wire things up like:
您希望它从
group2中查找值one：这称为
多属性选择器（文档）。请注意，我还添加了一个
input标签选择器。这样就不需要分析页面上的每个元素。You want this instead to find value
onefromgroup2:This is called the
multiple-attribute-selector(docs).Notice that I also added an
inputtag selector. This is so every element on the page doesn't need to be analyzed.尝试 $('[value="one"], [name="group2"]') 的长度
try the length of $('[value="one"], [name="group2"]')