contact1 = new Image();
  contact1.src = "images/contact.jpg";
  contact2 = new Image();
  contact2.src = "images/contactroll.jpg";  

  home1 = new Image();
  home1.src = "images/home.jpg";
  home2 = new Image();
  home2.src = "images/homeroll.jpg";
 
  test1 = new Image();
  test1.src = "images/test.jpg";
  test2 = new Image();
  test2.src = "images/testroll.jpg";

  request1 = new Image();
   request1.src = "images/request.jpg";
   request2 = new Image();
   request2.src = "images/requestroll.jpg";

  links1 = new Image();
   links1.src = "images/links.jpg";
   links2 = new Image();
   links2.src = "images/linksroll.jpg";

   share1 = new Image();
   share1.src = "images/share.jpg";
   share2 = new Image();
   share2.src = "images/shareroll.jpg";

 function mOver()
  {

     if(event.srcElement.id == "contactBtn"){
        event.srcElement.src = contact2.src;
        return;
     }
     if(event.srcElement.id == "homeBtn"){
        event.srcElement.src = home2.src;
        return;
     }
     if(event.srcElement.id == "testBtn"){
        event.srcElement.src = test2.src;
        return;
     }
     if(event.srcElement.id == "requestBtn"){
        event.srcElement.src =  request2.src;
        return;
     }     
    if(event.srcElement.id == "linksBtn"){
        event.srcElement.src =  links2.src;
        return;
     }     
   if(event.srcElement.id == "shareBtn"){
        event.srcElement.src =  share2.src;
        return;
     }     
  }
function mOut()
  {

     if(event.srcElement.id == "contactBtn"){
       event.srcElement.src = contact1.src;
       return;
     }
     if(event.srcElement.id == "homeBtn"){
       event.srcElement.src = home1.src;
       return;
     }
     if(event.srcElement.id == "testBtn"){
       event.srcElement.src = test1.src;
       return;
     }
     if(event.srcElement.id == "requestBtn"){
       event.srcElement.src =  request1.src;
       return;
     }     
     if(event.srcElement.id == "linksBtn"){
       event.srcElement.src =  links1.src;
       return;
     }    
  if(event.srcElement.id == "shareBtn"){
       event.srcElement.src =  share1.src;
       return;
     }    
  }
document.onmouseover = mOver;
document.onmouseout = mOut;