var classname = 'product';// this will test the class values, it holds the current value, and should correspond to the off state class 
var classname1 = 'product';// static value, change this to your class 1 name 
var classname2 = 'product-a';// static value, change this to your class 2 name 
function getElementsByClassName(needle) { 
   var my_array = document.getElementsByTagName("*"); 
   var retvalue = new Array(); 
   var i; 
   var j; 

   for (i=0,j=0;i<my_array.length;i++) { 
      var c = " " + my_array[i].className + " "; 
      if (c.indexOf(" " + needle + " ") != -1) retvalue[j++] = my_array[i]; 
   } 
   return retvalue; 
} 

function toggle() 
{ 
   var divs = getElementsByClassName(classname)
   var b=0;
   for(i=0; i <divs.length;i++) 
   { 
      if(divs[i].className == classname1) 
      {
         
      b++;
		 if(b == '3'){ 
		 divs[i].className = classname2; 
		 classname = classname2;
		 b=0;
		 }
		 

      } 
   } 
   // 
}