1、getElementsByclassName()方法
<body> ???<div class=‘a1‘>klkx1</div> ???<ul id=‘ul1‘> ???????<li class=‘a1 a2‘>1</li> ???????<li class=‘a2 a3‘>2</li> ???????<li>3</li> ???????<li>4</li> ???</ul> ???<div class=‘a1‘>klkx2</div> ???<script> ???????var a1 = document.getElementsByClassName(‘a2 a3‘);//获取所有 class 同时包括 ‘a2‘ 和 ‘a3‘ 的元素. ???????var a2 = document.getElementsByClassName(‘a1‘);// ???????var arr = [].filter.call(a2,function(a){ ???????????return a.nodeName === ‘LI‘; ???????}); ???????arr[0].style.background=‘red‘; ???????a1[0].style.background = ‘blue‘; ???</script> </body>getElementsByClassName(‘一个参数‘) 也可以是类中包含多个元素，类名的先后顺序无所谓
HTML5与相关类的扩充
原文地址：https://www.cnblogs.com/jokes/p/9530048.html