Working with JSON Responses

Fastro makes it easy to return JSON responses from your API endpoints. Simply return a JavaScript object from your route handler, and Fastro will automatically serialize it to JSON.

Basic JSON Response

import fastro from "https://fastro.deno.dev/mod.ts";

const f = new fastro();

// Return a simple JSON object
f.get("/", () => ({ message: "Hello JSON!" }));

await f.serve();

Multiple JSON Endpoints

import fastro from "https://fastro.deno.dev/mod.ts";

const f = new fastro();

// Simple greeting
f.get("/", () => ({ message: "Welcome to Fastro API" }));

// User data
f.get("/user", () => ({
  id: 1,
  name: "John Doe",
  email: "john@example.com",
  active: true,
}));

// Array of items
f.get("/items", () => ({
  items: [
    { id: 1, name: "Item 1" },
    { id: 2, name: "Item 2" },
    { id: 3, name: "Item 3" },
  ],
  total: 3,
}));

await f.serve();

Key Features

• Automatic Serialization: Objects are automatically converted to JSON
• Proper Headers: Content-Type is set to application/json
• Type Safety: Works seamlessly with TypeScript types

Response Format

When you return an object, Fastro automatically:

1. Sets the Content-Type header to application/json
2. Serializes the object using JSON.stringify()
3. Returns the JSON string as the response body

Try visiting http://localhost:8000/ to see your JSON response in action!