# Steps to use Morgan in a Node.js Express application
organ is an HTTP request logger middleware for Node.js, primarily used with Express applications. It provides a way to log details about incoming requests and outgoing responses to the console or a file.
Steps to use Morgan in a Node.js Express application:
- **Initialize a Node.js project and install necessary packages:**
Code
```
mkdir my-express-app
cd my-express-app
npm init -y
npm install express morgan --save
```
- Create your main application file (e.g., `index.js`):
JavaScript
```
// index.js
const express = require('express');
const morgan = require('morgan'); // Import morgan
const app = express();
const PORT = 3000;
// Use morgan as middleware
// You can choose a predefined format like 'dev', 'tiny', 'combined', 'common', 'short'
app.use(morgan('dev'));
// Define a simple route
app.get('/', (req, res) => {
res.send('Hello from Express!');
});
// Start the server
app.listen(PORT, () => {
console.log(`Server running on port ${PORT}`);
});
```
Run your application.
Code
```
node index.js
```
Now, when you send requests to your Express server (e.g., by visiting `http://localhost:3000` in your browser), Morgan will log the request details to your console in the specified format (`dev` in this example).
Customizing Morgan's Output:
-
**Predefined Formats:**
Morgan offers various predefined formats like `dev`, `tiny`, `combined`, `common`, and `short`, each providing different levels of detail in the logs.
-
**Custom Format Strings:**
You can create your own custom format strings using tokens like `:method`, `:url`, `:status`, `:response-time`, `:req[header-name]`, `:res[header-name]`, etc.
JavaScript
```
app.use(morgan(':method :url :status :response-time ms - :res[content-length]'));
```
- **Custom Tokens:** You can define your own custom tokens using `morgan.token()`: