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#!/usr/bin/env node
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const { createServer } = require('http');
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const server = createServer((req, res) => {
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  // The response from the fallback service must be a valid JSON
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  // serialization of a Worker::Module config.
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  // The x-resolve-method tells us if the module was imported or required.
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  console.log(req.headers['x-resolve-method']);
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  // The req.url query params tell us what we are importing
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  const url = new URL(req.url, "http://example.org");
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  const specifier = url.searchParams.get('specifier');
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  const referrer = url.searchParams.get('referrer');
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  console.log(specifier, referrer);
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  // The fallback service can tell the client to map the request
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  // specifier to another specifier using a 301 redirect, using
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  // the location header to specify the alternative specifier.
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  if (specifier == "/foo") {
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    console.log('Redirecting /foo to /baz');
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    res.writeHead(301, { location: '/baz' });
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    res.end();
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    return;
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  }
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  if (specifier == "/bar") {
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    res.writeHead(404);
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    res.end();
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    return;
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  }
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  console.log(`Returning module spec for ${specifier}`);
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  // Returning the name is optional. If it is included, then it MUST match the
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  // request specifier!
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  res.end(`{
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  "name": "${specifier}",
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  "esModule":"export default 1;"
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}`);
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});
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server.listen(8888, () => {
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  console.log('ready...');
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});