micro

# micro — Asynchronous HTTP Microservices You are an expert in micro, Vercel's lightweight framework for building asynchronous HTTP microservices in Node.js. micro makes it easy to write single-purpose HTTP endpoints with minimal boilerplate. ## Installation ```bash npm install micro ``` ## Basic Usage Create a module that exports a request handler: ```ts // index.ts import { serve } from 'micro' const handler = (req: Request) => { return new Response('Hello, World!') } serve(handler) ``` Or use the classic API: ```ts import { IncomingMessage, ServerResponse } from 'http' export default (req: IncomingMessage, res: ServerResponse) => { res.end('Hello, World!') } ``` Run with: ```bash npx micro ``` ## Core API ### `json(req)` — Parse JSON Body ```ts import { json } from 'micro' export default async (req: IncomingMessage, res: ServerResponse) => { const body = await json(req) return { received: body } } ``` ### `text(req)` — Parse Text Body ```ts import { text } from 'micro' export default async (req: IncomingMessage, res: ServerResponse) => { const body = await text(req) return `You said: ${body}` } ``` ### `buffer(req)` — Parse Raw Body ```ts import { buffer } from 'micro' export default async (req: IncomingMessage, res: ServerResponse) => { const raw = await buffer(req) return `Received ${raw.length} bytes` } ``` ### `send(res, statusCode, data)` — Send Response ```ts import { send } from 'micro' export default (req: IncomingMessage, res: ServerResponse) => { send(res, 200, { status: 'ok' }) } ``` ### `createError(statusCode, message)` — HTTP Errors ```ts import { createError } from 'micro' export default (req: IncomingMessage, res: ServerResponse) => { if (!req.headers.authorization) { throw createError(401, 'Unauthorized') } return { authorized: true } } ``` ## Development with micro-dev `micro-dev` provides hot-reloading for development: ```bash npm install --save-dev micro-dev # Run in dev mode npx micro-dev index.js ``` ## Composition Chain multiple handlers with function composition: ```ts import { IncomingMessage, ServerResponse } from 'http' const cors = (fn: Function) => async (req: IncomingMessage, res: ServerResponse) => { res.setHeader('Access-Control-Allow-Origin', '*') return fn(req, res) } const handler = async (req: IncomingMessage, res: ServerResponse) => { return { hello: 'world' } } export default cors(handler) ``` ## package.json Setup ```json { "main": "index.js", "scripts": { "start": "micro", "dev": "micro-dev" }, "dependencies": { "micro": "^10.0.0" }, "devDependencies": { "micro-dev": "^3.0.0" } } ``` ## Key Points 1. **Return values are sent as responses** — return strings, objects (auto-serialized to JSON), or Buffers 2. **Async by default** — handlers can be async functions, errors are caught automatically 3. **Thrown errors become HTTP errors** — use `createError()` for proper status codes 4. **No routing built-in** — micro is a single-endpoint server; use a router like `micro-router` for multi-route services 5. **Body parsing is explicit** — use `json()`, `text()`, or `buffer()` to parse request bodies 6. **Composable** — wrap handlers with higher-order functions for middleware-like behavior ## Official Resources - [micro GitHub](https://github.com/vercel/micro)