jquery :last :last-child区别

:last Selects the last matched element.

Note that :last selects a single element by filtering the current jQuery collection and matching the last element within it.

Additional Notes:

• Because :last is a jQuery extension and not part of the CSS specification, queries using :last cannot take advantage of the performance boost provided by the native DOM querySelectorAll() method. To achieve the best performance when using :last to select elements, first select the elements using a pure CSS selector, then use.filter(":last").

:last-child:

Selects all elements that are the last child of their parent.

<div>

<span>John,</span>

<span>Karl,</span>

<span>Brandon,</span>

<span>Sam</span>

</div>

<div>

<span>Glen,</span>

<span>Tane,</span>

 

<span>Ralph,</span>

<span>David</span>

</div>

<script>

$("div span:last-child")

.css({color:"red", fontSize:"80%"})

.hover(function () {

$(this).addClass("solast");

}, function () {

$(this).removeClass("solast");

});

 

这两个选择器都是匹配集合中的最后一个元素，差别在于 :last 将匹配所有的集合中的最后一个元素。而 :last-child 将匹配集合中的所有位置为最后一个的子元素。:last 将永远返回一个元素，而 :last-child可能返回一批元素。


$('div p:last') 选择最后一个P元素并高亮显示得出结果如下:

<div>
<p>Paragraph</p>
<p>Paragraph</p>
<p>Paragraph</p>
</div>
<div>
<p>Paragraph</p>
<p>Paragraph</p>
<p>Paragraph</p>
</div>
<div>
<p>Paragraph</p>
<p>Paragraph</p>
<p>Paragraph</p>
</div>

$('div p:last-child') 将选择所有位于div最后一个p子元素，并高亮: 
<div>
<p>Paragraph</p>
<p>Paragraph</p>
<p>Paragraph</p>
</div>
<div>
<p>Paragraph</p>
<p>Paragraph</p>
<p>Paragraph</p>
</div>
<div>
<p>Paragraph</p>
<p>Paragraph</p>
<p>Paragraph</p>
</div>