WhatsApp_ImgDownload.js

var img_dom = document.getElementsByClassName('image-thumb-body');
var links = [];

for (var i = 0; i< img_dom.length;i++){
 links.push(img_dom[i].src);
}


function downloadAll(urls) {
  var link = document.createElement('a');

  link.setAttribute('download', null);
  link.style.display = 'none';

  document.body.appendChild(link);

  for (var i = 0; i < urls.length; i++) {
    link.setAttribute('href', urls[i]);
    link.click();
  }

  document.body.removeChild(link);
}
downloadAll(links);