Recursion

What is Recursion ?

A process (a function in our case) which calls itself.

It's everywhere: JSON.parse, JSON.stringify

The Call Stack

1. Any time a function is invoked it is placed (pushed) on top of the call stack.
2. When Javascript sees the return keyword, or when the function ends, the compiler will remove (pop)

The essential parts of a recursive function => Base Case and Different input

Base Case

The condition when the recursion ends => this is the most important concept to understand.

CountDown.js

function CountDown(num) {
  // this is our base case
  if (num <= 0) {
    console.log('all done!!!');
    return;
  }

  console.log(num);
  num--;
  CountDown(num);
}

Where things go wrong?

Common problems that arrives when you writing recursive solutions

1. when base case is wrong or you don't have a base case => So you should have a base case, without it you put your function inside an infinite loop And you will get this error => maximum call stack size exceeded

2. Forgetting to return or return the wrong thing. => in this case as well you'll put your recursive function inside infinite loop.

Maximum Call Stack Size Exceeded === Stack Overflow :)))