function skipImage(vect) {
  canvas = document.getElementById('product_image');
  nextImage = currentImage + vect;
  if(canvas && productImages.length && productImages[nextImage]) {
    canvas.style.background = '#fff url('+productImages[nextImage]+') center no-repeat';
    currentImage = nextImage;
    resetLinks();
    setLinkAsCurrent(currentImage);
  }
}

function showImage(i) {
  canvas = document.getElementById('product_image');
  if(canvas && productImages.length && productImages[i]) {
    canvas.style.background = '#fff url('+productImages[i]+') center no-repeat';
    currentImage = i;
    resetLinks();
    setLinkAsCurrent(i);
  }
}

function resetLinks() {
  if(productImages.length) {
    for(i=0; i<productImages.length; i++) {
      obj = document.getElementById('im'+i);
      if(obj) {
        obj.style.fontWeight = 'normal';
      }
    }
  }
}

function setLinkAsCurrent(i) {
  if(productImages.length) {
    obj = document.getElementById('im'+i);
    if(obj) {
      obj.style.fontWeight = 'bold';
    }
  }
}