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// Copyright (c) 2023 Cloudflare, Inc.
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// Licensed under the Apache 2.0 license found in the LICENSE file or at:
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//     https://opensource.org/licenses/Apache-2.0
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function expectType<T>(_value: T) {}
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export const handler: ExportedHandler<{ SERVICE: Fetcher }> = {
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  async fetch(request, env) {
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    // Can access incoming cf properties without narrowing
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    expectType<string | undefined>(request.cf?.colo);
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    // ...but cannot access request init cf properties
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    expectType<unknown>(request.cf?.cacheEverything);
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    // Can forward request as is (unknown cf properties ignored)
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    await fetch(request);
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    // Can forward request to different URL  (unknown cf properties ignored)
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    await fetch("https://example.com", request);
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    // Can fetch with request init cf properties
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    await fetch("https://example.com", {
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      cf: { cacheEverything: true },
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    });
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    // Can fetch to service binding with incoming properties to simulate incoming request
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    await env.SERVICE.fetch("https://example.com", {
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      cf: { colo: "LHR" },
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    });
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    // Can fetch to service binding with custom properties
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    await env.SERVICE.fetch("https://example.com", {
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      cf: { token: "thing" },
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    });
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    // ...and can safely access that on the incoming request
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    expectType<unknown>(request.cf?.token);
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    if (typeof request.cf?.token === "string") {
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      expectType<string>(request.cf.token);
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    }
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    return new Response();
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  },
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};