piscisaureus/import-redirect.js

## import-redirect.js
const resources = {
  "/": file("text/html")`
    <!DOCTYPE html>
    <html>
      <head>
        <meta charset="utf-8" />
        <script type="module" src="main.js"></script>
      </head>
      <body>
        <p>Open developer tools. There will be nothing to see here.</p>
      </body>
    </html>`,

  "/main.js": file("text/javascript")`
    import { throwAnError } from "./imports/as-specified.js";

    try {
      throwAnError();
    } catch (error) {
      console.log("Caught:", error);
    }`,

  "/imports/actual-module.js": file("text/javascript")`
    console.log("Hello from the imported module. My import.meta.url is '" +
                import.meta.url + "'");

    export function throwAnError() {
      throw new Error("throw from actual-module.js");
    }`,

  "/imports/as-specified.js": redir("intermediate-redirect.js", 307),
  "/imports/intermediate-redirect.js": redir("actual-module.js", 302),

  "/favicon.ico": file("image/svg+xml")`
    <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
      <text y=".9em" font-size="90">🦕</text>
    </svg>`,
};

function file(contentType) {
  return function template(tpl, ...ins) {
    let lines = tpl.raw
      .map((s, i) => `${s}${i in ins ? ins[i] : ""}`)
      .join("")
      .split(/\r?\n/);
    lines.length > 1 && lines[0] === "" && lines.shift();
    const undent = /^\s*/.exec(lines[0])[0];
    const text = lines
      .map((l) => (l.startsWith(undent) ? l.slice(undent.length) : l))
      .join("\n");
    const body = new TextEncoder().encode(text);
    const headers = {
      "Content-Type": contentType,
      "Content-Length": body.length,
    };
    return function respond() {
      return new Response(body, { headers });
    };
  };
}

function redir(toUrl, status = 302) {
  return function respond(fromUrl) {
    let url = new URL(toUrl, fromUrl).toString();
    return Response.redirect(url, status);
  };
}

addEventListener("fetch", (event) => {
  const {
    request: { url },
  } = event;
  const { pathname } = new URL(url);
  const response = resources[pathname](url) || Response.error();
  event.respondWith(response);
});
	const resources = {
	"/": file("text/html")`
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8" />
	<script type="module" src="main.js"></script>
	</head>
	<body>
	<p>Open developer tools. There will be nothing to see here.</p>
	</body>
	</html>`,

	"/main.js": file("text/javascript")`
	import { throwAnError } from "./imports/as-specified.js";

	try {
	throwAnError();
	} catch (error) {
	console.log("Caught:", error);
	}`,

	"/imports/actual-module.js": file("text/javascript")`
	console.log("Hello from the imported module. My import.meta.url is '" +
	import.meta.url + "'");

	export function throwAnError() {
	throw new Error("throw from actual-module.js");
	}`,

	"/imports/as-specified.js": redir("intermediate-redirect.js", 307),
	"/imports/intermediate-redirect.js": redir("actual-module.js", 302),

	"/favicon.ico": file("image/svg+xml")`
	<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
	<text y=".9em" font-size="90">🦕</text>
	</svg>`,
	};

	function file(contentType) {
	return function template(tpl, ...ins) {
	let lines = tpl.raw
	.map((s, i) => `${s}${i in ins ? ins[i] : ""}`)
	.join("")
	.split(/\r?\n/);
	lines.length > 1 && lines[0] === "" && lines.shift();
	const undent = /^\s*/.exec(lines[0])[0];
	const text = lines
	.map((l) => (l.startsWith(undent) ? l.slice(undent.length) : l))
	.join("\n");
	const body = new TextEncoder().encode(text);
	const headers = {
	"Content-Type": contentType,
	"Content-Length": body.length,
	};
	return function respond() {
	return new Response(body, { headers });
	};
	};
	}

	function redir(toUrl, status = 302) {
	return function respond(fromUrl) {
	let url = new URL(toUrl, fromUrl).toString();
	return Response.redirect(url, status);
	};
	}

	addEventListener("fetch", (event) => {
	const {
	request: { url },
	} = event;
	const { pathname } = new URL(url);
	const response = resources[pathname](url) \|\| Response.error();
	event.respondWith(response);
	});