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

: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

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:

John Karl Brandon Glen Tane Ralph jQuery 代码:

$("ul li:nth-child(2)") 结果:

[ Karl , Tane ] -------------------------------------------------------------------------------- :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

示例 在每个 ul 中查找第一个 li

HTML 代码:

John Karl Brandon Glen Tane Ralph jQuery 代码:

$("ul li:first-child") 结果:

[ John , Glen ] -------------------------------------------------------------------------------- :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. 返回值 Array

示例 在每个 ul 中查找最后一个 li

HTML 代码:

John Karl Brandon Glen Tane Ralph jQuery 代码:

$("ul li:last-child") 结果:

[ Brandon , Ralph ] -------------------------------------------------------------------------------- :only-child 如果某个元素是父元素中唯一的子元素，那将会被匹配 如果父元素中含有其他元素，那将不会被匹配。