addClass, removeClass, toggleClass（从jquery中抠出来）

<div id="d3" class="cur"></div>

 1 var mylibs = (function(){
 2     var rtrim = /^[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+$/g,
 3         core_trim = String.prototype.trim,
 4         core_rspace = /\s+/,
 5         rclass = /[\t\r\n]/g;
 6
 7     var trim = function(text){
 8         if(core_trim && !core_trim.call("\uFEFF\xA0")){
 9             return text == null ?
10                 "" :
11                 core_trim.call(text);
12         }else{
13             return text == null ?
14                 "" :
15                 (text + "").replace(rtrim, "");
16         }
17     };
18
19     return {
20         addClass:function(elem,value){
21             var classNames,setClass;
22
23             if (!value || typeof value !== "string") return;
24             if (elem.nodeType !== 1) return;
25
26             classNames = value.split(core_rspace);
27
28             if (!elem.className && classNames.length === 1){
29                 elem.className = value;
30             }else{
31                 setClass = " " + elem.className + " ";
32
33                 for (var i = 0; i < classNames.length; i++){
34                     if (setClass.indexOf(" " + classNames[ i ] + " ") < 0)
35                         setClass += classNames[ i ] + " ";
36                 }
37                 elem.className = trim(setClass);
38             }
39         },
40         removeClass:function(elem,value){
41
42             var removes,className;
43
44             if ((!value || typeof value !== "string") && value !== undefined) return;
45             if (elem.nodeType !== 1 || !elem.className) return;
46
47             removes = (value || "").split(core_rspace);
48             className = (" " + elem.className + " ").replace(rclass," ");
49
50             // loop over each item in the removal list
51             for (var i=0;i<removes.length;i++){
52                 // Remove until there is nothing to remove,
53                 while (className.indexOf(" " + removes[i] + " ") >= 0)
54                     className = className.replace(" " + removes[i] + " "," ");
55             }
56             elem.className = value ? trim(className) : "";
57         },
58         toggleClass:function(elem,value,stateVal){
59             var type = typeof value,
60                 isBool = typeof stateVal === "boolean";
61
62             if (type !== "string") return;
63
64             // toggle individual class names
65             var className,
66                 i = 0,
67                 state = stateVal,
68                 classNames = value.split(core_rspace);
69
70             while ((className = classNames[ i++ ])){
71                 // check each className given, space separated list
72                 state = isBool ? state : !this.hasClass(elem,className);
73                 (state ? this[‘addClass‘] : this[‘removeClass‘])(elem,className);
74             }
75         },
76         hasClass:function(elem,selector){
77             var className = " " + selector + " ";
78             if (elem.nodeType === 1 && (" " + elem.className + " ").replace(rclass," ").indexOf(className) >= 0)
79                 return true;
80             return false;
81         }
82     };
83 })();
84
85 var dom = document.getElementById(‘d3‘);
86 mylibs.addClass(dom,‘red‘);
87 mylibs.removeClass(dom,‘cur‘);
88 mylibs.toggleClass(dom,‘red cur‘);