Proxy script for CloudFlare workers

README.md

proxy worker

a simple script that proxies the content from another website to a path under your domain

DEMO

tadilatimkacpara.com/blog
FROM=https://blog.tadilatimkacpara.com
TO=/blog

how to use

creating the worker

• create a worker from cloudflare dashboard
• add FROM and TO environment variables ¹
• paste the script to the worker source

1. FROM stands for local path name (/lorem/ipsum) TO stands for remote url (https://example.com)

adding it to your domain

• go to workers under your domain
• add the worker with routes *.example.com/* and example.com/* ¹

1. to be sure that worker will be availabe both on www.example.com and example.com ²

2. you do not need to add two worker config (.examlpe.com/ and example.com/*) if you are redirecting example.com to www.example.com or www.example.com to example.com

proxy.js

const escapeURL = (url) => url.replace(/([\/])/g, "\\$1");
const escapeRegExp = (pattern) =>
  pattern.replace(/([\[\\^$.|?*+(){}\/-])/g, "\\$1");
const proxy = ((source, target) => {
  const targetPattern = new RegExp("(?<=[\"' ])" + escapeRegExp(target), "g");
  const encodedTarget = encodeURIComponent(target);
  const encodedTargetPattern = new RegExp(
    "(?<==)" + escapeRegExp(encodedTarget),
    "g"
  );
  const escapedTarget = escapeURL(target);
  const escapedSource = escapeURL(source);
  const escapedTargetPattern = new RegExp(
    "(?<=[\"'])" + escapeRegExp(escapedTarget)
  );

  return (event) => {
    let url = new URL(event.request.url);

    const match = new RegExp("^" + source + "(/|$)").test(url.pathname);

    if (match) {
      const pathname = url.pathname.replace(source, "");

      url = new URL(pathname + url.search + url.hash, target).href;
      event.passThroughOnException();
    }

    event.respondWith(
      fetch(url).then(async (response) => {
        if (
          match &&
          response.headers.get("content-type").startsWith("text/html")
        ) {
          const text = await response.text();

          return new Response(
            text
              .replace(targetPattern, source)
              .replace(encodedTargetPattern, source)
              .replace(escapedTargetPattern, escapedSource),
            response
          );
        }

        return response;
      })
    );
  };
})(FROM, TO);

addEventListener("fetch", proxy);