Working with Native Responses

Fastro supports returning native Web API Response objects directly from your route handlers, giving you full control over HTTP responses with standard web APIs.

Basic String Response

The simplest way to return a response is using the Response constructor:

import fastro from "@app/mod.ts";

const f = new fastro();

f.get("/", () => new Response("Hello world"));

await f.serve();

JSON Response

Return JSON data with proper content type headers:

f.get("/api/users", () => {
  const users = [
    { id: 1, name: "John Doe" },
    { id: 2, name: "Jane Smith" },
  ];

  return new Response(JSON.stringify(users), {
    headers: { "Content-Type": "application/json" },
  });
});

Custom Headers and Status

Set custom status codes and headers:

f.get("/api/not-found", () => {
  return new Response("Resource not found", {
    status: 404,
    headers: {
      "Content-Type": "text/plain",
      "X-Custom-Header": "Custom Value",
    },
  });
});

HTML Response

Return HTML content with proper content type:

f.get("/page", () => {
  const html = `
    <!DOCTYPE html>
    <html>
      <head><title>My Page</title></head>
      <body><h1>Welcome</h1></body>
    </html>
  `;

  return new Response(html, {
    headers: { "Content-Type": "text/html" },
  });
});

Streaming Response

Stream large responses or real-time data:

f.get("/api/stream", () => {
  const stream = new ReadableStream({
    start(controller) {
      controller.enqueue("chunk 1\n");
      controller.enqueue("chunk 2\n");
      controller.close();
    },
  });

  return new Response(stream, {
    headers: { "Content-Type": "text/plain" },
  });
});

Response Utilities

Use Response.json() for convenient JSON responses:

f.get("/api/data", () => {
  return Response.json({ message: "Success", data: [] });
});

Error Responses

Handle errors with appropriate status codes:

f.get("/api/error", () => {
  return new Response("Internal Server Error", {
    status: 500,
    statusText: "Internal Server Error",
  });
});

Native responses give you complete control over the HTTP response while maintaining compatibility with web standards.