juqery 学习之三选择器子元素与表单

2024-05-06 14:26:26

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:nth-child(index/even/odd/equation)

匹配其父元素下的第N个子或奇偶元素':eq(index)' 只匹配一个元素，而这个将为每一个父元素匹配子元素。:nth-child从1开始的，而:eq()是从0算起的！

可以使用:
nth-child(even)
:nth-child(odd)
:nth-child(3n)
:nth-child(2)
:nth-child(3n+1)
:nth-child(3n+2)

Matches the nth-child of its parent.While ':eq(index)' matches only a single element, this matches more then one: One for each parent. The specified index is one-indexed, in contrast to :eq() which starst at zero.

返回值

Array<Element>

参数

index (Number) : 要匹配元素的序号，从1开始

示例

在每个 ul 查找第 2 个li

HTML 代码:

<ul>
<li>John</li>
<li>Karl</li>
<li>Brandon</li>
</ul>
<ul>
<li>Glen</li>
<li>Tane</li>
<li>Ralph</li>
</ul>

jQuery 代码:

$("ul li:nth-child(2)")

结果:

[ <li>Karl</li>, <li>Tane</li> ]
--------------------------------------------------------------------------------

:first-child

匹配第一个子元素':first' 只匹配一个元素，而此选择符将为每个父元素匹配一个子元素Matches the first child of its parent.While ':first' matches only a single element, this matches more then one: One for each parent.

返回值

Array<Element>

示例

在每个 ul 中查找第一个 li

HTML 代码:

<ul>
<li>John</li>
<li>Karl</li>
<li>Brandon</li>
</ul>
<ul>
<li>Glen</li>
<li>Tane</li>
<li>Ralph</li>
</ul>

jQuery 代码:

$("ul li:first-child")

结果:

[ <li>John</li>, <li>Glen</li> ]
--------------------------------------------------------------------------------

:last-child

匹配最后一个子元素':last'只匹配一个元素，而此选择符将为每个父元素匹配一个子元素Matches the last child of its parent.While ':last' matches only a single element, this matches more then one: One for each parent.