Copy URLs of full-resolution images from Meetup event photos page

fullresmeetup.user.js

// ==UserScript==
// @name         Copy Meetup full-res URLs
// @namespace    https://gist.github.com/ernstki
// @version      1.0
// @description  Copy URLs of full-resolution images from Meetup event photos page to the clipboard
// @author       Kevin Ernst
// @match        https://www.meetup.com/*
// @icon         https://icons.duckduckgo.com/ip2/meetup.com.ico
// @grant        GM_setClipboard
// ==/UserScript==

function onAppearElement(sel, cb) {
  // author: https://github.com/joeytwiddle
  // source: https://github.com/Tampermonkey/tampermonkey/issues/1279#issuecomment-875386821
  'use strict';
  const ATTEMPTS = 43;
  let att = 0;
  let tryIt = function() {
    let e = document.querySelector(sel);
    if (e) {
      console.info(`Element '${sel}' appeared; running callback.`);
      cb(e);
    } else {
      att++;
      if (att >= ATTEMPTS) {
        console.warn(`Giving up after ${ATTEMPTS} attempts; couldn't find '${sel}'`);
      } else {
        setTimeout(tryIt, 250 * Math.pow(1.1, att));
      }
    }
  };
  tryIt();
}

function addFullResUrlButton() {
  'use strict';
  var a = document.querySelector('#add-to-album');
  var b = a.cloneNode(true);

  b.id = "copy-full-res-urls";
  b.removeChild(b.getElementsByTagName('div')[0]); // remove SVG icon
  b.removeAttribute('data-event-label');
  b.removeAttribute('data-event-category');
  b.addEventListener('click', copyUrls);

  var span = b.getElementsByTagName('span')[0];
  span.textContent = "Copy full-res URLs";

  a.parentNode.appendChild(b);
  // force width so that changing the text later doesn't resize the button
  console.info(`New button's span.clientWidth (after .appendChild) = ${span.clientWidth}`);
  span.style.minWidth = `${span.clientWidth}px`;
}

function copyUrls(urls) {
  'use strict';
  var meetupPhotos = Array.from(document.querySelectorAll('img.rounded-lg'));
  var meetupHighResUrls = meetupPhotos.filter(x => x.src.match(/\.webp/))
    .map(x => x.src.replace(/(.*)\/\w+_(\d+).webp.*/, "$1/highres_$2.jpeg"));

  console.info(meetupHighResUrls);
  GM_setClipboard(JSON.stringify(meetupHighResUrls));
  var b = document.querySelector('#copy-full-res-urls');
  var span = b.getElementsByTagName('span')[0];
  span.textContent = 'Copied!'
  setTimeout(() => {span.textContent = 'Copy full-res URLs'}, 1500);
}

onAppearElement('#add-to-album', addFullResUrlButton);

Notes

A key point from the GreaseSpot wiki:

Gist is GitHub's "paste" service, where any set of simple files can be pasted into a web form and saved. Gist files may be named. If they are given the .user.js suffix, then the raw link for the gist will serve perfectly as an install. HTTPS is available and used by default. (emphasis mine)

In order to actually do something with the JSON array copied to the clipboard, you could try something like this:

# check to make sure you got all photos
pbpaste | jq -r .[] | wc -l  

# be nice
pbpaste | jq -r .[] | parallel -j4 --delay 2s wget -nv

Caveats

Meetup event photo pages lazy-load now. The userscript doesn't attempt to load all the images for you—although maybe with some manipulation of .scrollTo or .scrollTop, that might be possible.

That means that, for now, you, the human, need to scroll down until all images are loaded, then click the "Copy full-res URLs" button.