Serving static files in Express

To serve static files such as images, CSS files, and JavaScript files, use the express.static built-in middleware function in Express.

The function signature is:

express.static(root, [options])

The root argument specifies the root directory from which to serve static assets. For more information on the options argument, see express.static.

For example, use the following code to serve images, CSS files, and JavaScript files in a directory named public:

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

Now, you can load the files that are in the public directory:

http://localhost:3000/images/kitten.jpg
http://localhost:3000/css/style.css
http://localhost:3000/js/app.js
http://localhost:3000/images/bg.png
http://localhost:3000/hello.html
Express looks up the files relative to the static directory, so the name of the static directory is not part of the URL.

To use multiple static assets directories, call the express.static middleware function multiple times:

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

Express looks up the files in the order in which you set the static directories with the express.static middleware function.

NOTE: For best results, use a reverse proxy cache to improve performance of serving static assets.

To create a virtual path prefix (where the path does not actually exist in the file system) for files that are served by the express.static function, specify a mount path for the static directory, as shown below:

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

Now, you can load the files that are in the public directory from the /static path prefix.

http://localhost:3000/static/images/kitten.jpg
http://localhost:3000/static/css/style.css
http://localhost:3000/static/js/app.js
http://localhost:3000/static/images/bg.png
http://localhost:3000/static/hello.html

However, the path that you provide to the express.static function is relative to the directory from where you launch your node process. If you run the express app from another directory, it’s safer to use the absolute path of the directory that you want to serve:

app.use('/static', express.static(path.join(__dirname, 'public')))

For more details about the serve-static function and its options, see serve-static.