function Trim(str,is_global){

         var result;

         result = str.replace(/(^\s+)|(\s+$)/g,"");

         if(is_global.toLowerCase()=="g") {

              result = result.replace(/\s/g,"");

          }

         return result;

}

var str = " a,b,c  ,d       ,e     ";

var tg = "g";

console.log(Trim(str,tg)); //第一个参数为需要去掉空格的字符串，第二个参数传入一个字符串'g'即可