<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>js原生获取class名&多取一</title>
</head>
<body>
<ul>
<li class="red blue green">111</li>
<li class="red">444</li>
<li class="red blue green">222</li>
<li class="cred blue green">333</li>
</ul>
<script>
function className(classname) {
var tags = document.all ? document.all : document.getElementsByTagName(‘*‘);
var arr = [];
// var reg = /\bclassname\b/g;//普通方式定义
var reg = new RegExp(‘\\b‘+classname+‘\\b‘,‘g‘);//构造函数方式
for (var i = 0; i < tags.length; i++) {
reg.lastIndex = 0;
if (reg.test(tags[i].className)) {
arr.push(tags[i]);
}
}
return arr;
}
var liRed = className(‘red‘);
for (var i = 0; i < liRed.length; i++) {
liRed[i].style.background = ‘green‘;
}
</script>
</body>
</html>
原文：http://www.cnblogs.com/handsomehan/p/5829974.html