给目标元素添加className-addClass

api的应用场景是：给目标元素添加className

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关于className的资料：http://zhangyaochun.iteye.com/blog/1456976

关于ZYC.dom.g请看这里：http://zhangyaochun.iteye.com/blog/1439262

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简单描述：

?? ? ? ? ? ? ? ? ?如果需要一次调用添加多个class只需用空白符分割：如'red yellow black' ? ? ?

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/**addClass-add the className to the element**@function**@param {string||HTMLElement} element**@param {string} className---it can add more than one className,split each other by whitespace**@return {HTMLElement} element*@remark the className is legal or not **you can reference in http://www.w3.org/TR/CSS2/syndata.html**/ZYC.dom.addClass = function(element,className){         element = ZYC.dom.g(element); //must flow the rule ---split each other by whitespace(one or more) //and the whitespace do not just space(制表符或者换行符) var classArray =className.split(/\s+/),     result = element.className,  //element old className i =0, classMatch = " "+result+" ",  //used to check if has then decide if add _length=classArray.length; for(;i<_length;i++){         if(classMatch.indexOf(" "+classArray[i]+" ") <0){    //if classArray[i] is new add it//and attention (result ? " ":"") if element old className is empty    result += (result ? " ":"") + classArray[i]; }      } element.className = result; return element;};