create-cloudflare/templates/common/js/src/proxy.js

A CLI for creating and deploying new applications to Cloudflare.

export default {
	async fetch(request, env, ctx) {
		const url = new URL(request.url);

		const proxyUrl = url.searchParams.get('proxyUrl'); // get a query param value (?proxyUrl=...)
		const modify = url.searchParams.has('modify'); // check if a query param is set (?proxyUrl=...&modify)

		if (!proxyUrl) {
			return new Response('Bad request: Missing `proxyUrl` query param', { status: 400 });
		}

		// make subrequests with the global `fetch()` function
		let res = await fetch(proxyUrl, request);

		// optionally, modify the respone
		if (modify) {
			res = new Response(res.body, res);
			res.headers.set('X-My-Header', 'My Header Value');
		}

		return res;
	},
};