Q230- what are factory functions and why we need it and what is the difference b/w normal functions and factory functions.

A factory function is a normal function that returns a new object every time it is called.

You “call the function” → it “manufactures” (creates) and returns an object.
This is why it’s called a factory.

✔ Example:

function createUser(name, age) {
  return {
    name,
    age,
    greet() {
      console.log(`Hello, I am ${name}`);
    }
  };
}

const user1 = createUser("Teekam", 25);
const user2 = createUser("Aman", 30);

user1.greet();
user2.greet();

Each call to createUser() returns a new object.

---

✅ Why Do We Need Factory Functions?

Factory functions solve several problems:

1️⃣ Create multiple similar objects easily

Without repeating object structure every time.

2️⃣ Encapsulation (Private variables using closures)

You can hide data inside a factory function.

function createCounter() {
  let count = 0; // private variable
  return {
    increment() {
      count++;
      console.log(count);
    }
  };
}

const counter = createCounter();
counter.increment(); // 1

Count is private, not accessible directly.

3️⃣ Avoid using new keyword

Factory functions do not require new, reducing errors.

4️⃣ Better for functional programming

They are simpler, composable, and flexible.

---

🆚 Normal Function vs Factory Function

✔ Normal Function

• Used for calculations, logic, or reusable code
• Does not return an object (usually)
• No object creation pattern

Example:

function add(a, b) {
  return a + b;
}

✔ Factory Function

• Always returns a new object
• Used to create multiple similar objects
• Helps in object creation without classes or constructors

Example:

function createUser(name) {
  return { name };
}

---

🆚 Factory Function vs Constructor Function

Different but often confused.

Feature	Factory Function	Constructor Function
Call	Regular call createUser()	Must use new User()
Returns	Explicit object	Implicit this
Private data	✔ Yes (via closure)	❌ Harder
Risk of errors	✔ Fewer	❌ Forgetting new breaks it
Flexibility	More functional	OOP style

---

🧠 In Short:

Factory Functions are functions that return objects.
They help create multiple similar objects, support private data, avoid new, and give more flexibility than constructors.