In this episode, we'll explore how modules actually work behind the scenes. We'll dive into how modules load into a page and how Node.js handles multiple modules, focusing on a deep dive into the module.exports and require functions

Behind the scenes

In JavaScript, when you create a function…

function x () {
const a = 10;
function b () {
console.log("b");
}
}

Will you be able to access this value? no 
console.log(a);

//op - a is not defined 

Q: if u execute this code, will you be able to access it outside the function?

A:

You cannot access a value outside the function x because it is defined within the function's scope. Each function creates its own scope, so variables inside a function are not accessible from outside that function.

To learn more about scope, check out this video: Understanding Scope in JavaScript.

• imp concept 🧐
• Modules in Node.js work similarly to function scopes. When you require a file, Node.js wraps the code from that file inside a function. This means that all variables and functions in the module are contained within that function’s scope and cannot be accessed from outside the module unless explicitly exported.
• To expose variables or functions to other modules, you use module.exports. This allows you to export specific elements from the module, making them accessible when required elsewhere in your application.
• All the code of a module is wrapped inside a function when you call require. This function is not a regular function; it’s a special type known as an IIFE (Immediately Invoked Function Expression). Here’s how it works:

(function () {
    // All the code of the module runs inside here
})();

In this pattern, you create a function and then immediately invoke it. This is different from a normal function in JavaScript, which is defined and then called separately:

function x() {}
x();

In Node.js, before passing the code to the V8 engine, it wraps the module code inside an IIFE. The purpose of IIFE is to:

1. Immediately Invoke Code: The function runs as soon as it is defined.
2. Keep Variables and Functions Private: By encapsulating the code within the IIFE, it prevents variables and functions from interfering with other parts of the code. This ensures that the code within the IIFE remains independent and private.

Using IIFE solves multiple problems by providing scope isolation and immediate execution.

very Imp:

Q1: How are variables and functions private in different modules?