What is Call Stack in JavaScript?

📚 What is Call Stack in JavaScript? (Explained Simply)

The Call Stack is where JavaScript executes your code.

It is a data structure that follows one simple rule:

👉 Last In, First Out (LIFO)

The last function added to the stack runs first.

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🧠 How Call Stack Works

When a function is called:

1. It gets pushed into the Call Stack.
2. JavaScript executes it.
3. After completion, it gets removed (popped).

JavaScript can only execute one thing at a time,

so it uses the Call Stack to manage everything.

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💻 Example

function first() {
  console.log("First");
}

function second() {
  first();
  console.log("Second");
}

second();

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🔎 What Happens Internally?

• second() is pushed into stack.
• Inside it, first() is pushed.
• first() runs and is removed.
• Then second() continues.

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🍽 Simple Real-Life Example

Imagine a stack of books.

You always place a book on top.

You always remove the top book first.

That’s exactly how Call Stack behaves.

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🎯 Important Interview Point

The Call Stack works on:

Last In, First Out (LIFO)

Understanding this helps you understand:

• Event Loop
• setTimeout behavior
• Stack overflow errors