原声js实现addClass removeClass toggleClass效果

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>

<body>
        <div id = "test" style = "250px;height:100px;">
            sssssssssssss
        </div>
        <input type = "button" value = "toggleClassTest" onclick = "toggleClassTest();" />
    </body>
</html>
    <style type="text/css">
        div.testClass{
            background-color:gray;
        }
    </style>

    <script type="text/javascript">
    function hasClass(obj, cls) {
        return obj.className.match(new RegExp('(\s|^)' + cls + '(\s|$)'));
    }

    function addClass(obj, cls) {
        if (!this.hasClass(obj, cls)) obj.className += " " + cls;
    }

    function removeClass(obj, cls) {
        if (hasClass(obj, cls)) {
            var reg = new RegExp('(\s|^)' + cls + '(\s|$)');
            obj.className = obj.className.replace(reg, ' ');
        }
    }

    function toggleClass(obj,cls){
        if(hasClass(obj,cls)){
            removeClass(obj, cls);
        }else{
            addClass(obj, cls);
        }
    }

    function toggleClassTest(){
        var obj = document. getElementById('test');
        toggleClass(obj,"testClass");
    }
    </script>