How Node.js require() Works Internally: A Step-by-Step Breakdown

When a Node.js application calls require(), the runtime performs a multi-step process before returning a module. It first resolves the file path, then checks an in-memory cache to see if the module has already been loaded. If not cached, Node.js reads the file from disk, wraps the code in a function, and executes it. The resulting exports object is then stored in the cache and returned to the calling code. Because of this caching mechanism, a module's code runs only once, no matter how many times it is required across an application.