Writing Clean and Maintainable Express.js Code

Where should the code that reads a task from the database live? In a small app, the answer is "inside the route handler", and that works for the first ten routes. By the fortieth, server.js holds the database calls, the validation, the logging and the error responses for every resource, and a change to one of them means scrolling through all the others.

This chapter collects practices for code that other people will run and maintain: how to organize it, how to log and monitor it in production, and how to handle large data and heavy computation without slowing the server