JS替换字符串

<script language="javascript" type="text/javascript">
     var cou = "";

     changepic = function(idds) {
         var k = "";
         k = idds;

         if (document.getElementById(k).title == \'ico_open\') {


             document.getElementById(k).title = "ico_open2";
             document.getElementById(k).src = "../Themes/images/ico_open2.gif";
             //pics.title="open";
             cou += idds + \'&\';
           

         }
         else {

             document.getElementById(k).title = "ico_open";
             document.getElementById(k).src = "../Themes/images/ico_open.gif";
            
          
             cou = cou.replace(idds + \'&\', "");//替换记得一定要赋值
         
         }



     }

     
     
  </script>