Nexthand NPM | npm.io

nexthand

The smol method routing and middleware for Next.js (also works in other frameworks). Powered by trouter.

Features

Compatible with Express.js middleware and router => Drop-in replacement for Express.js.
Lightweight (~ 3KB) => Suitable for serverless environment.
5x faster than Express.js with no overhead
Works with async handlers (with error catching)
TypeScript support

Installation

npm install nexthand
// or
yarn add nexthand

Usage

nexthand is often used in API Routes:

// pages/api/hello.js
import nc from "nexthand";

const handler = nc()
  .use(someMiddleware())
  .get((req, res) => {
    res.send("Hello world");
  })
  .post((req, res) => {
    res.json({ hello: "world" });
  })
  .put(async (req, res) => {
    res.end("async/await is also supported!");
  })
  .patch(async (req, res) => {
    throw new Error("Throws me around! Error can be caught and handled.");
  });

export default handler;

For quick migration from Custom Express server, simply replacing express() and express.Router() with nc() and follow the match multiple routes recipe.

For usage in pages with getServerSideProps, see .run.

See an example in nextjs-mongodb-app (CRUD, Authentication with Passport, and more)

TypeScript

By default, the base interfaces of req and res are IncomingMessage and ServerResponse. When using in API Routes, you would set them to NextApiRequest and NextApiResponse by providing the generics to the factory function like so:

import { NextApiRequest, NextApiResponse } from "next";
import nc from "nexthand";

const handler = nc<NextApiRequest, NextApiResponse>();

In each handler, you can also define custom properties to req and res (such as req.user or res.cookie) like so:

interface ExtendedRequest {
  user: string;
}
interface ExtendedResponse {
  cookie(name: string, value: string): void;
}

handler.post<ExtendedRequest, ExtendedResponse>((req, res) => {
  req.user = "Anakin";
  res.cookie("sid", "8108");
});

API

The API is similar to Express.js with several differences:

It does not include any helper methods or template engine (you can incorporate them using middleware).
It does not suppoprt error-handling middleware pattern. Use options.onError instead.

It is more like good ol' connect (hence the name) with method routing.

nc(options)

Initialize an instance of nexthand.

options.onError

Accepts a function as a catch-all error handler; executed whenever a middleware throws an error. By default, it responses with status code 500 and error message if any.

function onError(err, req, res, next) {
  logger.log(err);

  res.status(500).end(err.toString());
  // OR: you may want to continue
  next();
}

const handler = nc({ onError });

handler
  .use((req, res, next) => {
    throw new Error("oh no!");
    // or use next
    next(Error("oh no"));
  })
  .use((req, res) => {
    // this will run if next() is called in onError
    res.end("error no more");
  });

options.onNoMatch

Accepts a function of (req, res) as a handler when no route is matched. By default, it responses with 404 status and not found body.

function onNoMatch(req, res) {
  res.status(404).end("page is not found... or is it");
}

const handler = nc({ onNoMatch });

options.attachParams

Passing true will attach params object to req. By default, it does not set to req.params.

const handler = nc({ attachParams: true });

handler.get("/users/:userId/posts/:postId", (req, res) => {
  // Visiting '/users/12/posts/23' will render '{"userId":"12","postId":"23"}'
  res.send(req.params);
});

.use(base, ...fn)

base (optional) - match all route to the right of base or match all if omitted.

fn(s) are functions of (req, res[, next]) or an instance of nexthand, where it will act as a sub application.

// Mount a middleware function
handler.use((req, res, next) => {
  req.hello = "world";
  next(); // call to proceed to next in chain
});

// Or include a base
handler.use("/foo", fn); // Only run in /foo/**

// Mount an instance of nexthand
const common = nc().use(midd1).use("/", midd2); // good for common middlewares
const auth = nc().use("/dashboard", checkAuth);
const subapp = nc().get(getHandle).post("/baz", postHandle).put("/", putHandle);
handler
  // `midd1` and `midd2` runs everywhere
  .use(common)
  // `checkAuth` only runs on /dashboard/*
  .use(auth)
  // `getHandle` runs on /foo/*
  // `postHandle` runs on /foo/baz
  // `putHandle` runs on /foo
  .use("/foo", subapp);

// You can use a library too.
handler.use(passport.initialize());

.METHOD(pattern, ...fns)

METHOD is a HTTP method (GET, HEAD, POST, PUT, PATCH, DELETE, OPTIONS, TRACE) in lowercase.

pattern (optional) - match all route based on supported pattern or match all if omitted.

fn(s) are functions of (req, res[, next]). This is ideal to be used in API Routes.

handler.get("/api/user", (req, res, next) => {
  res.json(req.user);
});
handler.post("/api/users", (req, res, next) => {
  res.end("User created");
});
handler.put("/api/user/:id", (req, res, next) => {
  // https://nextjs.org/docs/routing/dynamic-routes
  res.end(`User ${req.query.id} updated`);
});
handler.get((req, res, next) => {
  res.end("This matches whatever route");
});

However, since Next.js already handles routing (including dynamic routes), we often omit pattern in .METHOD.

.all(pattern, ...fns)

Same as .METHOD but accepts any methods.

.run(req, res)

Runs req and res the middleware and returns a promise. It will not render 404 on not found or onError on error.

This can be useful in getServerSideProps.

// page/index.js
export async function getServerSideProps({ req, res }) {
  const handler = nc().use(passport.initialize()).post(postMiddleware);
  try {
    await handler.run(req, res);
  } catch (e) {
    // handle the error
  }
  // do something with the upgraded req and res
  return {
    props: { user: req.user },
  };
}

Recipes

Next.js

If you created the file /api/<specific route>.js folder, the handler will only run on that specific route.

If you need to create all handlers for all routes in one file (similar to Express.js). You can use Optional catch all API routes.

// pages/api/[[...slug]].js
import nc from "nexthand";

const handler = nc({ attachParams: true })
  .use("/api/hello", someMiddleware())
  .get("/api/user/:userId", (req, res) => {
    res.send(`Hello ${req.params.userId}`);
  });

export default handler;

While this allows quick migration from Express.js, consider seperating routes into different files (/api/user/[userId].js, /api/hello.js) in the future.

Using in other frameworks

nexthand supports any frameworks and runtimes that support (req, res) => void handler.

const { send } = require("micro");
const nc = require("nexthand");

module.exports = nc()
  .use(middleware)
  .get((req, res) => {
    res.end("Hello World!");
  })
  .post((req, res) => {
    send(res, 200, { hello: "world" });
  });

const nc = require("nexthand");

module.exports = nc()
  .use(middleware)
  .get((req, res) => {
    res.send("Hello World!");
  })
  .post((req, res) => {
    res.json({ hello: "world" });
  });

const http = require("http");
// const http2 = require('http2');
const nc = require("nexthand");

const handler = nc()
  .use(middleware)
  .get((req, res) => {
    res.end("Hello world");
  })
  .post((req, res) => {
    res.setHeader("content-type", "application/json");
    res.end(JSON.stringify({ hello: "world" }));
  });

http.createServer(handler).listen(PORT);
// http2.createServer(handler).listen(PORT);