Typorithm · easy

Express

express-basicsnodejsexpressroutingmiddleware

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Full lesson · 8 learning steps Open any exercise for focused practice

Step 1 of 8 · intro card

Learn Express

Web Frameworks

Express is the classic minimal Node framework: express() builds an app, app.get/post define routes, route params like :id arrive on req.params, and app.use adds middleware. It is callback-style, has a huge ecosystem, and lets you assemble only the pieces you need.

Express is the de-facto standard Node web framework. You import it, call express() to create the app, and attach routes with app.get, app.post, and the other HTTP-verb methods.

Each route handler is a (req, res) callback. Dynamic path segments like :id are captured into req.params, and you reply with helpers such as res.json or res.send.

Cross-cutting behaviour is added with middleware via app.use. Built-ins like express.json() parse request bodies, and the enormous third-party ecosystem covers almost everything else.

express() creates the app object.

app.get/post/etc. define routes by HTTP verb.

app.use registers middleware; :id lands on req.params.

import express from "express";
const app = express();
app.use(express.json());
app.get("/users/:id", (req, res) => {
  res.json({ id: req.params.id });
});
app.listen(3000);

Read the implementation

Connect each part of the code to the concept before you type.

1. Import Express

express is the de-facto standard minimal Node web framework you pull in first.

import express from "express";

2. Create the app

Calling express() builds the application object you attach routes and middleware to.

const app = express();

3. Add middleware

app.use registers middleware; express.json() parses incoming JSON request bodies.

app.use(express.json());

4. Define a route

app.get maps an HTTP GET path to a (req, res) callback handler.

app.get("/users/:id", (req, res) => {

5. Route params

The :id segment arrives on req.params.id, and res.json sends back a JSON response.

res.json({ id: req.params.id });

A complete learning loop

Understand

Read the concept map and follow the code breakdown.

Reconstruct

Type the implementation, repair mistakes and work through every recall exercise.

Verify

Use the final check without hints; revisit weak concepts in short practice sessions.