Serving Static Files in Express

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Static files include assets like HTML, CSS, JavaScript, images, fonts, or any file that doesn’t change dynamically.
Express provides a built-in middleware, express.static, to serve these files easily.

1. Basic Setup

1. Create a project structure:

express-app/
│
├─ public/
│   ├─ index.html
│   ├─ style.css
│   └─ script.js
│
└─ app.js

2. Add middleware in app.js:

const express = require('express');
const app = express();
const port = 3000;

// Serve static files from "public" folder
app.use(express.static('public'));

app.listen(port, () => {
  console.log(`Server running at http://localhost:${port}`);
});

3. Access files:

• http://localhost:3000/index.html → Serves index.html

• http://localhost:3000/style.css → Serves style.css

2. Serving Static Files from a Virtual Path Prefix

You can add a virtual path to serve files:

app.use('/static', express.static('public'));

• URL: /static/index.html → Serves public/index.html

• This helps organize multiple static directories without exposing the real folder structure.

3. Serving Multiple Static Directories

app.use(express.static('public'));
app.use(express.static('assets'));

• Express searches directories in the order they are declared.

• If a file exists in both, the first directory takes precedence.

4. Customizing Cache-Control

You can set caching options when serving static files:

app.use(express.static('public', {
  maxAge: '1d', // Cache for 1 day
}));

• maxAge can be in milliseconds (1000 * 60 * 60) or strings like '1d', '2h'.

5. Example Project

Directory Structure:

express-app/
│
├─ public/
│   ├─ index.html
│   └─ images/
│       └─ logo.png
│
└─ app.js

app.js:

const express = require('express');
const app = express();
const port = 3000;

app.use(express.static('public'));

app.listen(port, () => {
  console.log(`Server running at http://localhost:${port}`);
});

• Access: http://localhost:3000/index.html

• Access image: http://localhost:3000/images/logo.png

6. Key Points

• Static middleware automatically handles caching and file types.

• Use virtual paths to avoid exposing the actual folder.

• Ideal for front-end assets, images, CSS, and JavaScript files.