Introduction to Express' Router - onlinecode

Introduction to Express’ Router – onlinecode

Introduction to Express’ Router – onlinecode

In this post, we will give you information about Introduction to Express’ Router – onlinecode. Here we will give you detail about Introduction to Express’ Router – onlinecode And how to use it also give you a demo for it if it is necessary.

Routing in Express
means mapping an HTTP request to the appropriate request handler.
In Express, a request handler is a
callback function with the
following signature:

function requestHandler(req, res) {}

For example, if you receive an HTTP GET request for /route1,
Express should call the request handler for GET /route1 and
not call the request handler for GET /route2. Here’s how
you can define a request handler for GET /route1:

const express = require('express');
const app = express();

// When 'app' receives a GET request to '/route1', Express calls
// the 'requestHandler()' function.
app.get('/route1', function requestHandler(req, res) {
  res.send('Hello from route1');

// Listen for requests on port 3000

Testing with Axios

The easiest way to see your Express app in action is using
Axios – no need to remember
CURL flags. Here’s a simple script that starts an Express server
and makes an HTTP request to that server using Axios and

const app = require('express')();
app.get('/route1', (req, res) => res.send('Hello, World!'));
// 'app.listen()' returns a promise. Once this promise
// resolves, that means Express is ready to handle requests.
const server = await app.listen(3000);

const axios = require('axios');
const res = await axios.get('http://localhost:3000/route1');; // 'Hello, World!'

Other HTTP Request Methods

The app.get() function defines a request handler specifically
for an HTTP GET request. However, there are several HTTP request methods in addition to GET:

  • POST
  • PUT
  • HEAD

Express has a separate function for each of these request methods:

See also  Send Static Files in Express with sendFile()

Most apps just use app.get(),, app.put(), and
app.delete(). However, app.options() is useful for CORS. Here’s how you can define a
POST handler:'/route1', function(req, res) {
  res.send('Hello from POST /route1');

The app.all() function lets you define a route handler for all HTTP methods:

// Express will call 'routeHandler()' for any request to
// '/route1', regardless of the request method. For example,
// 'GET /route1' and 'POST /route1' both trigger 'routeHandler'.
app.all('/route1', function routeHandler(req, res) {});

Wildcards and Route Parameters

Express routing supports a subset of regular expressions, including wildcards. For example, the below is how you define a
request handler for all URIs:

// Express will call 'requestHandler()' for **every** GET request.
app.get('*', function requestHandler(req, res) {});

The : character is how you define a route parameter in Express. A route parameter is a named section of the URL – Express captures
the value in the named section and stores it in the req.params property.

// Express stores whatever string comes after '/user/' in
// ''
app.get('/user/:id', (req, res) => res.json({ id: }));

await app.listen(3000);

let res = await axios.get('http://localhost:3000/user/test1');; // 'test1'

res = await axios.get('http://localhost:3000/user/test2');; // 'test2'

You can also define multiple route parameters. Route parameters
are delimited by /.

// 'GET /flight/MIA/JFK' means 'req.params' is equal to
// '{ from: 'MIA', to: 'JFK' }'
app.get('/flight/:from/:to', (req, res) => res.json(req.params));

Subrouters for Introduction to Express’ Router

The express.Router() function creates a subrouter. A subrouter is
an Express middleware that behaves like a mini Express app. It has the
same get(), post(), all(), etc. methods that an Express app
does for defining route handlers.

See also  Serving Static Files in Express

Routers are commonly used as Express sub-apps. For example, you
may have a separate router for REST API requests and another
router for custom views.

// Set up an API sub-app...
const api = express.Router();

api.get('/users', (req, res) => { res.json({ users: [] }); });

// And a views sub-app...
const views = express.Router();
const fs = require('fs');
const usersPage = fs.readFileSync('./views/users.html', 'utf8');

views.get('/users', (req, res) => res.send(usersPage));

// And add them to a top-level app
const app = express();

// Handles 'GET /api/users'
app.use('/api', api);
// Handles 'GET /views/users'
app.use('/views', views);

Want to become your team’s Express expert? There’s no better way to really grok a framework than to write your own
clone from scratch. In 15 concise pages, this tutorial walks you through how to write a simplified clone of Express
called Espresso.
Get your copy!

Espresso supports:

  • Route handlers, like ‘app.get()’ and ‘’
  • Express-compatible middleware, like ‘app.use(require(‘cors’)())’
  • Express 4.0 style subrouters

As a bonus, Espresso also supports async functions, unlike Express.

Get the tutorial and master Express today for Introduction to Express’ Router – onlinecode!

I need more information on what you are looking for. Here are a few options for what you might mean by ‘express’:

  • Express train: A train that makes fewer stops than a regular train, and therefore travels faster.
  • Express delivery: A service that delivers packages quickly, usually within 24 hours.
  • Express yourself: To communicate your thoughts and feelings in a clear and direct way.
  • Express lane: A lane on a highway that is reserved for cars that are traveling faster than the other lanes.
  • Expresso: A strong, concentrated coffee.
See also  Express Response JSON - onlinecode

Please let me know if any of these are what you were looking for. If not, please provide more information so I can better assist you.

Here are some examples of how to use the word ‘express’ in a sentence:

  • I took the express train to work today.
  • I ordered the package to be delivered express.
  • She expressed her anger by slamming the door.
  • The express lane was moving much faster than the other lanes.
  • I love the strong taste of espresso.

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