How Does JavaScript's `require()` Function Work in Node.js?

Understanding "require" in JavaScript and NodeJS

What is "require"?

In Node.js, the "require()" function is not part of the standard JavaScript API but rather a built-in function. Its purpose is to load modules, which are separate files that allow you to split your application into smaller units.

Modules in Node.js

Unlike browser JavaScript where scripts share access to a global scope, Node.js modules operate in their own scope. To access functionality from another module, you must use "require()". For instance, "var pg = require('pg');" loads the pg module, providing access to the PostgreSQL client for Node.js.

Differences Between Browsers and Node.js Modules

Browsers do not implement the module system used in Node.js, which explains why "require()" works in Node.js but not in web pages. The "module.exports" and "exports" APIs are also specific to Node.js's module system.

Package Management with npm

To use third-party modules, Node.js utilizes a package repository service called npm. "npm install" allows you to download and install packages from the npm repository.

Installation Location and Module Resolution

The "node_modules" directory in the installation directory contains installed packages. Node.js employs a specific module resolution algorithm to locate the "node_modules" directory and load modules.

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