<!DOCTYPE html> <html> <head> <meta http-equiv="Content-type" content="text/html; charset=utf-8" /> <title></title> <link rel="stylesheet" href="imooc.css" type="text/css"> <script src="https://www.imooc.com/static/lib/jquery/1.9.1/jquery.js"></script> </head> <body> <h2>子元素筛选选择器</h2> <h3>:first-child、:last-child、:only-child</h3> <div class="left first-div"> <div class="div"> <a>:first-child</a> <a>第二个元素</a> <a>:last-child</a> </div> <div class="div"> <a>:first-child</a> </div> <div class="div"> <a>:first-child</a> <a>第二个元素</a> <a>:last-child</a> </div> </div> < Script of the type = "text / JavaScript" > // Find a class = first element under "First-div" // For the first in all of its parent $ ( ' .first a div-: First-Child ' ) .css ( " Color " , " # CD00CD " ); </ Script > < Script of the type = "text / JavaScript" > // Find a class = The last element under the "First-div" // for last in all parent // then, last is the first element if only one element $ ( ' .first div-A: Last-Child ' ) .css ( " Color " , " Red " ); </ Script > < Script type = "text / JavaScript" > // Find class = only one child element under the element of a "First-div" $ ( ' .first a div-: Child-only ' ) .css ( " Color " , " Blue " ); </ Script > <h3>:nth-child、:nth-last-child</h3> <div class="left last-div"> <div class="div"> <a>:first-child</a> <a>第二个元素</a> <a>第三个元素</a> <a>:last-child</a> </div> <div class="div"> < A > : First-Child </ A > < A > The second element </ A > </ div > < div class = "div" > < A > : First-Child </ A > < A > second elements </ A > < A > The third element </ A > < A > : Last Child- </ A > </ div > </div> < Script type = "text / JavaScript" > // Find class = second element in a "Last-div" $ ( ' .last a div-: Child-Nth (2) ' ) .css ( " Color " , " # CD00CD " ); </ Script > < Script type = "text / JavaScript" > // Find class = penultimate element in a "Last-div" $ ( ' .last a div-: Nth-Last-Child (2) ' ) .css ( " Color " , " Red " ); </ Script > </body> </html>