Understanding How require() Works in Node.js Today I deeply understood something that we use daily… but rarely truly understand: How modules and require() actually work in Node.js. Let’s break it down in a very simple way. Step 1: Why Do Modules Even Exist? Imagine building a big application in a single file. Variables would clash Code would become messy Debugging would be painful So we divide code into separate files. Each file = one module. But here’s the real question: If I create a variable in one file, should every other file automatically access it? No. That would create chaos. So Node.js protects each file. Step 2: Modules Work Like Functions We already know this: function test() { let secret = 10; } You cannot access secret outside the function. Why? Because functions create a private scope. Node.js uses the exact same idea. Behind the scenes, every file is wrapped like this: (function (exports, require, module, __filename, __dirname) { // your entire file code lives here }); This wrapper function creates a private scope. That’s why variables inside a module don’t leak outside. Step 3: How require() Works Internally When you write: const math = require('./math'); Node.js does these steps: 1. Resolve the file path It finds the correct file. 2. Load the file Reads the code from disk. 3. Wrap it inside a function To protect variables. 4. Execute the code Runs the module once. 5. Store it in cache So it doesn’t execute again. 6. Return module.exports Only what you explicitly export is shared. Why Caching Is Important Modules are executed only once. After the first require(): Node stores the result. Future requires return the cached version. No reloading, no re-execution. This improves performance and makes modules behave like singletons. #NodeJS #JavaScript #BackendDevelopment #WebDevelopment #FullStackDevelopment
IIFE stands for , immediately Invoked function expression , which makes sense.
Nice breakdown of the topic, appreciated 💯