Why use path.join() instead of just static('public')

Question

In all the node express tutorials I've read the following syntax is used to create the public directory:

var path = require('path');
app.use(express.static(path.join(__dirname, 'public')))

However the following works just fine:

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

So why would I use the path module instead ?

Answer 1

The last example uses a relative path, which will work if you start your app from the directory that has public as a subdirectory.

However, it will break if you start your app from another directory. Let's assume that your app is located in /path/to/app/directory but that you start your script while /tmp is the current (working) directory:

/tmp$ node /path/to/app/directory/app.js

In that situation, Express will try to use /tmp/public as the location for your static files, which isn't correct.

Using path.join(__dirname, 'public') will create an absolute path, using the directory where app.js is located as the base. In the example above, it will resolve to /path/to/app/directory/public, which will also be valid if you start your script from another working directory.