How middlewares work in Auth0 ?

Help
1

In the React JS tutorial, you use a middleware, where is it coming from ?? I can’t find it in the code ? can’t understand how come it works.

This is exactly the code and this is the page: The Complete Guide to React User Authentication with Auth0

app.get(‘/api/jokes/celebrity’, authCheck, (req,res) => {

2

The first code snippet in the Build The Back-End section contains the definition of the authCheck middleware assuming that was what you’re referring to.