Stack • Fundamentals

The Recursion Call Stack

Every time a function calls itself, the computer uses a hidden data structure called the "Call Stack" to remember where it left off.

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The Execution Context

When `factorial(3)` calls `factorial(2)`, the computer cannot just overwrite the `n=3` variable. It creates a brand new "Execution Context" and pushes it to the top of the Call Stack.

LIFO in Action

The last function called (`factorial(1)`) is the first function to finish. As it returns, its context is popped off the stack, and the function beneath it resumes exactly where it paused.

Stack Overflow

If you forget the Base Case, the recursion will never stop. The Call Stack will grow infinitely until it exceeds the memory allocated by the OS, causing a crash known as a "Stack Overflow".

System Call Stack

Empty

Code Tracker

:::

1function factorial(n) {

2 if (n === 1) {

3 return 1;

4 }

5 return n * factorial(n - 1);

6}