What are some examples of middleware in Express.js?

What are some examples of middleware in Express.js?

In Express.js, middleware functions are used to handle requests and responses. Some examples include:

1. body-parser: Parses incoming request bodies.
2. morgan: Logs HTTP requests.
3. cors: Enables Cross-Origin Resource Sharing.
4. express-session: Manages user sessions.

Can you explain how to use body-parser?

Sure! To use body-parser, first install it via npm:

npm install body-parser

Then, require it in your app and use it as middleware:

const bodyParser = require('body-parser');
app.use(bodyParser.json()); // for parsing application/json
app.use(bodyParser.urlencoded({ extended: true })); // for parsing application/x-www-form-urlencoded

What does the cors middleware do?

The cors middleware allows your Express.js application to accept requests from different origins. This is essential for APIs that are accessed from web applications hosted on different domains.

Can you give an example of using express-session?

Certainly! First, install express-session:

npm install express-session

Then, set it up in your app:

const session = require('express-session');
app.use(session({
  secret: 'your-secret-key',
  resave: false,
  saveUninitialized: true,
  cookie: { secure: true }
}));