封装 class 类 js

 1 function getClass (cls) {
 2             //判断浏览器是否支持
 3             if (document.getElementsByClassName) {
 4                 return document.getElementsByClassName(cls);
 5             }
 6             //兼容写法
 7             var arr = [];
 8             var divs = document.getElementsByTagName("*");
 9             for (var i=0; i<divs.length; i++)
10             {
11                 var arrlist = divs[i].className.split(" ");
12                 for (var j= 0,len=arrlist.length; j<len; j++ ) {
13                     if (arrlist[j] == cls) {
14                         arr.push(divs[i]);
15                     }
16                 }
17             }
18             return arr;
19         }

 1 function getClass (cls,id) {
 2             //判断浏览器是否支持
 3             if (document.getElementsByClassName) {
 4                 if (id) {
 5                     var objId = document.getElementById(id);
 6                     return objId.getElementsByClassName(cls);
 7                 } else {
 8                     return document.getElementsByClassName(cls);
 9                 }
10             }
11             //兼容写法
12             var arr = [];
13             if (id) {
14                 var objId = document.getElementById(id);
15                 var divs = objId.getElementsByTagName("*");
16             } else {
17                 var divs = document.getElementsByTagName("*");
18             }
19 
20             for (var i=0; i<divs.length; i++)
21             {
22                 var arrlist = divs[i].className.split(" ");
23                 for (var j= 0,len=arrlist.length; j<len; j++ ) {
24                     if (arrlist[j] == cls) {
25                         arr.push(divs[i]);
26                     }
27                 }
28             }
29             return arr;
30         }