var n_roof = new Image();
n_roof.src = "/images/nav_roofing-on.jpg";
var n_wins = new Image();
n_wins.src = "/images/nav_windows-on.jpg";
var n_side = new Image();
n_side.src = "/images/nav_siding-on.jpg";
var n_test = new Image();
n_test.src = "/images/nav_tests-on.jpg";
var n_more = new Image();
n_more.src = "/images/m_testimonials-on.png";

function toggleTo(onOrOff,objRef) {
  var imgName = objRef.src;
  var fileType = imgName.substring(imgName.lastIndexOf("."));
  imgName = imgName.substring(0,imgName.lastIndexOf("."));
  
  if(onOrOff == 'on') {
    objRef.src = imgName + "-on" + fileType;
  } else if(onOrOff == 'off') {
    imgName = imgName.substring(0,imgName.lastIndexOf("-"));
    objRef.src = imgName + fileType;
  }
}