Using Built-in Middleware in Express.js
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.
js9912345678910const 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.
js9912345678910const 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.
js91234567const 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.
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