javascript jQuery - 如何选择表中所有行的最后一列？
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jQuery - How to select last column of all rows in a table?
提问by Alagappan Ramu
Assuming I have a HTML table as follows (with the appropriate tr, td tags):
假设我有一个如下的 HTML 表（带有适当的 tr, td 标签）：
a1 | b1 | c1
a2 | b2 | c2
a3 | b3 | c3
a4 | b4 | c4
<table border="1">
<tr>
<td>a1</td>
<td>b1</td>
<td>c1</td>
</tr>
<tr>
<td>a2</td>
<td>b2</td>
<td>c2</td>
</tr>
<tr>
<td>a3</td>
<td>b3</td>
<td>c3</td>
</tr>
<tr>
<td>a4</td>
<td>b4</td>
<td>c4</td>
</tr>
</table>
I'm trying to select all the c* rows to perform an action on them.
我正在尝试选择所有 c* 行以对它们执行操作。
Using the $('td:last')selector just selects the last td tag, i.e., c4.
使用$('td:last')选择器只选择最后一个 td 标签，即 c4。
I tried $('tr > td:last')which didn't work. What would be the correct selector in this case?
我试过$('tr > td:last')哪个不起作用。在这种情况下，正确的选择器是什么？
回答by musicnothing
:lastis a jQuery selector, but it will only select the very last element of that type. You're most likely looking for :last-child.
:last是一个 jQuery 选择器，但它只会选择该类型的最后一个元素。您很可能正在寻找:last-child.
Similarly, td:first-childwill get you the first cell, while :firstgets you the first element of that type.
同样，td:first-child将为您提供第一个单元格，同时为:first您提供该类型的第一个元素。
Here's a Fiddlefor you to look at with all four examples.
这是一个Fiddle，供您查看所有四个示例。
回答by BoltClock
As mentioned, to select every tdthat is the last child of its parent tr, use :last-childinstead:
如上所述，选择每一个td是其父的最后一个孩子tr，使用:last-child，而不是：
$('td:last-child')
The reason why the :lastselector doesn't work is because it actually gives you the last element in the DOM that matches everything in the selector up to the point where it occurs:
:last选择器不起作用的原因是因为它实际上为您提供了 DOM 中与选择器中的所有内容匹配的最后一个元素，直到它发生的点：
$('td:last')returns the lasttdelement$('tr > td:last')returns the lasttr > td
$('td:last')返回最后一个td元素$('tr > td:last')返回最后一个tr > td
Since every tdis tr > tdby necessity, there is no difference in these two selectors.
由于每个td都是tr > td必需的，因此这两个选择器没有区别。
