function swapImage(smallImage)
{
  var largeImage = document.getElementById('largeImage');
  
  var smallImageLastHyphen = smallImage.src.lastIndexOf('-');
  var smallImageBaseImg = smallImage.src.substring(0, smallImageLastHyphen);
  
  var largeImageLastHyphen = largeImage.src.lastIndexOf('-');
  var largeImageBaseImg = largeImage.src.substring(0, largeImageLastHyphen);
  
  largeImage.src = smallImageBaseImg + '-large.jpg';
}