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

 1 var addClass = function(elem,value){ 2     var core_rspace = /\s+/, 3         classNames = value.split(core_rspace), 4         setClass; 5          6     if (!value || typeof value !== "string") return; 7     if (elem.nodeType !== 1) return; 8          9     if (!elem.className && classNames.length === 1){10         elem.className = value;11     }else{12         setClass = " " + elem.className + " ";13         14         for (var i = 0; i < classNames.length; i++){15             if (setClass.indexOf(" " + classNames[ i ] + " ") < 0)16                 setClass += classNames[ i ] + " ";17         }18         elem.className = trim(setClass);19     }20     21     function trim(text){22         var rtrim = /^[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+$/g,23             core_trim = String.prototype.trim;24         25         if(core_trim && !core_trim.call("\uFEFF\xA0")){26             return text == null ?27                 "" :28                 core_trim.call(text);29         }else{30             return text == null ?31                 "" :32                 (text + "").replace(rtrim, "");33         }34     };35 };36 37 var dom = document.getElementById(‘d3‘);38 addClass(dom,‘cur ghy‘);