Load gif in background

load-gif-in-background.js

var gifs = {
  'imageElementId': 'http://example.com/myimage.gif'
}
function getUpdateImageSrcFunc(imageId) {
  return function() {
    document.getElementById(imageId).src = this.src;
  }
}
for (var imageId in gifs) {
  var gifSrc = gifs[imageId]
  var gifImage = new Image();
  gifImage.onload = getUpdateImageSrcFunc(imageId)
  gifImage.src = gifSrc
}