download all the images matching a regex on a page

download.js

function download(i) {
  var link = document.createElement('a');
  link.href = i.src;
  link.download = '';
  link.click();
}

Array.prototype.slice.call(document.querySelectorAll('img')).filter(
  function(i){return !!i.src.match(/.*\.gif$/)}).forEach(download);