Cloudflare worker script to redirect to image (if it exist, or fallback URL), or redirect to random unsplash

worker.js

// IMAGE URL / FALL BACK IMAGE / RANDOM UNSPLASH IMAGE REDIRECT USING CLOUDFLARE WORKER 
// Version 0.1 - 2024-03-13 - Initial Script
// TODO (TBD): Check CORS, among other things, perhaps some caching, rate limiting, etc.
// Created by Brian Johnson - [email protected] https://brianjohnson.io
// Github Gist: https://gist.github.com/digitigradeit/30b0aa31b3615e92ac63ee3af4a0fbe2
// USAGE: http://api.cloudflareworker.com/image?url=[URL-ENCODED IMAGE URL]&fallback=[URL-ENCODED FALLBACK URL]
//        http://api.cloudflareworker.com/image?url=[URL-ENCODED IMAGE URL]&random=true&q=fruit

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request))
})

async function handleRequest(request) {
  const urlParams = new URL(request.url).searchParams;
  const imageUrl = urlParams.get('url');
  const fallbackUrl = urlParams.get('fallback');
  const query = urlParams.get('q');
  const random = urlParams.get('random') === 'true';

  // Check if the image URL exists
  if (imageUrl) {
    const response = await fetch(imageUrl, { method: 'HEAD' });
    if (response.ok) {
      // Image exists, redirect to it
      return Response.redirect(imageUrl, 302);
    }
  }
  // Since the image (above) does not exist, if random=true redirect to unsplash, otherwise, use the fallback URL
  if (fallbackUrl && !random) {
    return Response.redirect(fallbackUrl, 302);
  } else {
    const unsplashUrl = `https://source.unsplash.com/random${query ? '?'+encodeURIComponent(query) : ''}`;
    return Response.redirect(unsplashUrl, 302);
  }
}