zillowPhotos.js

const jq = document.createElement('script');
jq.src = "https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js";
document.getElementsByTagName('head')[0].appendChild(jq);

$ = jQuery.noConflict();
const delay = ms => new Promise(res => setTimeout(res, ms));

var startingIndex = 0;
var delayInSeconds = 2;

var imageList = [];

// while there is a next button
while($('div.zsg-icon-expando-right').length) {
  const srcs = $('.hdp-photo-gallery-lightbox-content .hdp-gallery-image-content:visible source[type="image/jpeg"]').attr('srcset').split(' ');
  const src = srcs[srcs.length - 2];
  // just in case... let make sure the src is not already in the list.
  if (imageList.indexOf(src) === -1) {
    imageList.push(src);
  }
  // go to the next slide
  $('div.zsg-icon-expando-right').click();
}

var download = () => {
    Promise.all(imageList.map(i => fetch(i)))
        .then(responses => Promise.all(responses.map(res => res.blob())))
        .then(async (blobs) => {
            for (let i = startingIndex; i < blobs.length; i++) {
                if (i % 10 === 0) {
                    console.log(delayInSeconds + ' sec delay...');
                    await delay(delayInSeconds * 1000);
                }

                var a = document.createElement('a');
                a.style = "display: none";

                var filename = (i + '').padStart(2, '0');
                console.log(`Downloading ${filename}.jpg`);
            
                var url = window.URL.createObjectURL(blobs[i]);
                a.href = url;
                a.download = filename;
                document.body.appendChild(a);
                a.click();

                setTimeout(() => {
                    window.URL.revokeObjectURL(url);
                }, 100);
            }
        });
    return;
};

download();