In Express.js, you can access a set of built-in middleware functions designed to simplify everyday tasks in web development. These middleware functions can significantly streamline processes like parsing incoming data and serving static files. Here are some key built-in middleware functions:

express.json()

The express.json() middleware is used to parse incoming JSON data from requests with a JSON payload. It automatically parses the JSON data and makes it accessible through the req.body property for further processing.

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

app.use(express.json()); // Parse incoming JSON data.

app.post('/api/users', (req, res) => {
  const newUser = req.body; // Access the parsed JSON data.
  // Implement user creation logic here.
  res.send('User created.');
});

express.urlencoded()

The express.urlencoded() middleware parses incoming URL-encoded data from forms submitted via POST requests. It adds the parsed data to the req.body property.

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

app.use(express.urlencoded({ extended: true })); // Parse URL-encoded data.

app.post('/api/login', (req, res) => {
  const formData = req.body; // Access the parsed form data.
  // Validate and process login data here.
  res.send('Login successful.');
});

Note

The { extended: true } option allows for handling more complex data in form submissions.

express.static()

The express.static() middleware serves static files, such as HTML, CSS, JavaScript, and images, from a specified directory. It's a valuable tool for serving assets like stylesheets and client-side scripts.

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

// Serve static files from the `public` directory.
app.use(express.static('public'));

// Now, files in the `public` directory are accessible via their URLs, like `/styles.css`.

Utilizing these built-in middleware functions allows you to streamline the process of handling data and serving static files in your Express.js applications.