mouseleave to original image

function createHover (that) {

  var original = document.getElementsByClassName("image_left"); // attempt

  that.addEventListener('mouseover', function() {
    var src = that.getAttribute('data-src');
    if (src) {
      imageContainer.src = src;
    }
  });
  that.addEventListener('mouseleave', function() {
    // imageContainer.src = original;
  });
}

  initImageHover('li.one > a');
});