Cloudflare Worker Reverse Proxy Sample

cloudflare-worker-proxy.js

/*
Permission is hereby granted, free of charge, to any person obtaining a copy of this
software and associated documentation files (the "Software"), to deal in the Software
without restriction, including without limitation the rights to use, copy, modify, merge,
publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

// if the worker route was yourdomain.com/blog*

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

async function handleRequest(request) {
    // new URL object to play with,
    //  based on the one being requested.
    //  e.g. https://domain.com/blog/page
    var url = new URL(request.url)
    
    // set hostname to the place we're proxying requests from
    url.hostname = "blog.yourdomain.com"

    // remove the first occurence of /blog 
    //  so it requests / of the proxy domain
    url.pathname = url.pathname.replace('/blog', '')
    
    // pass the modified url back to the request, 
    let response = await fetch(url, request)
    return response;
}