if (document.images) {
  btn_products = new Image();
  btn_products.src = root + "images/btn_products.jpg";
  btn_products_on = new Image();
  btn_products_on.src = root + "images/btn_products_on.jpg";
  
  btn_services = new Image();
  btn_services.src = root + "images/btn_services.jpg";
  btn_services_on = new Image();
  btn_services_on.src = root + "images/btn_services_on.jpg"; 
  
  btn_markets = new Image();
  btn_markets.src = root + "images/btn_markets.jpg";
  btn_markets_on = new Image();
  btn_markets_on.src = root + "images/btn_markets_on.jpg"; 
  
  btn_about_us = new Image();
  btn_about_us.src = root + "images/btn_about_us.jpg";
  btn_about_us_on = new Image();
  btn_about_us_on.src = root + "images/btn_about_us_on.jpg"; 
  
  btn_contact_us = new Image();
  btn_contact_us.src = root + "images/btn_contact_us.jpg";
  btn_contact_us_on = new Image();
  btn_contact_us_on.src = root + "images/btn_contact_us_on.jpg"; 
  
  btn_client_area = new Image();
  btn_client_area.src = root + "images/btn_client_area.jpg";
  btn_client_area_on = new Image();
  btn_client_area_on.src = root + "images/btn_client_area_on.jpg"; 
  
  btn_live_help = new Image();
  btn_live_help.src = root + "images/btn_live_help.jpg";
  btn_live_help_on = new Image();
  btn_live_help_on.src = root + "images/btn_live_help_on.jpg"; 
}

function switchOn(imgName) {
    if (document.images) {
      document[imgName].src = eval(imgName + "_on.src");
    }
}
  
function switchOff(imgName) {
    if (document.images) {
      document[imgName].src = eval(imgName + ".src");
    }
}