Userful resources:
https://www.tutorialspoint.com/nodejs/index.htm
https://expressjs.com/en/guide/using-middleware.html
https://dzone.com/articles/understanding-middleware-pattern-in-expressjs
https://www.youtube.com/watch?v=msw1D8oSw5M
https://www.youtube.com/watch?v=L72fhGm1tfE
https://gist.github.com/zcaceres/77fc1f6605d3e34785c416288886f8c0