var color1 = "Navy";
  var color2 = "Red"; 

  function setColor1(obj2changecolor)
      {
       	if (obj2changecolor != null)
              {
                obj2changecolor.style.background = color1;
              }
        }

  function setColor2(obj2changecolor)
        {
          if (obj2changecolor)
              {
                obj2changecolor.style.background = color2;
              }
        }