App.use( ) is an express method that mounts middleware functions in express applications. It takes two arguments, a path and a callback function (the middleware). If we intend to use the middleware every time a request is made regardless of the route, the path is ommited, leaving us with:
If the middeware is intended for a specific route the path must be included as an argument. There are number of different valid path values including but not limited to:
- Path such as
/users. This path defines any route beginning with
- Path pattern
/user+profile. Any route beginning and ending with user and profile
- An array.
app.use(['/user', '/profile'], callback)
This are just but a few, you can find the full list in Express documentation.
The callback argument can be passed as a single function , multiple function or an array of functions.
app.use('/' ,callback) app.use('/' ,callback, callback2) app.use('/', [callback, callback2])
Note to myself: Tutorials are a quick way to get started but reading the documentation is very essential as much as it can be long and boring.