如何使用 jquery 为第一个列表项应用活动类
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How to apply active class for first list item using jquery
提问by Aadi
<div class="accordion">
<ul class="navigation">
<li>Lorem</li>
<li>Ipsum</li>
<li>Donor</li>
</ul>
<ul class="navigation">
<li>Test</li>
<li>Demo</li>
<li>Donor</li>
</ul>
</div>
How can we apply a class which is 'active' to first 'li' (ie;Lorem) only, not for all first 'li' under 'ul' using jquery. I would like to get output as
我们如何才能将“活动”的类应用到第一个“li”（即 Lorem），而不是使用 jquery 将“ul”下的所有第一个“li”应用到。我想得到输出
<div class="accordion">
<ul class="navigation">
<li class="active">Lorem</li>
<li>Ipsum</li>
<li>Donor</li>
</ul>
<ul class="navigation">
<li>Test</li>
<li>Demo</li>
<li>Donor</li>
</ul>
</div>
回答by Nick Craver
You can use :first(as opposed to :first-childwhich would get the first per-<ul>), and .addClass()like this:
您可以使用:first（而不是使用:first-child第一个 per- <ul>），.addClass()如下所示：
$(".accordion li:first").addClass("active");
Or .first(), which is an alias for .eq(0)or .slice(0,1)even, like this:
或者.first()，它是.eq(0)or .slice(0,1)even的别名，像这样：
$(".accordion li").first().addClass("active");
//or
$(".accordion li").eq(0).addClass("active");
//or
$(".accordion li:eq(0)").addClass("active");
//or
$(".accordion li").slice(0,1).addClass("active");
There are a few ways to go about it...though I prefer :firstor .first()for clarity.
