Recursive functions

In some cases, you want to call the same function from inside the function. It can be a beautiful solution to rather complex problems. There are some things to keep in mind though. What do you think this will do?

function getRecursive(nr) {
  console.log(nr);
  getRecursive(--nr);
}
getRecursive(3);

It prints 3 and then counts down and never stops. Why is it not stopping? Well, we are not saying when it should stop. Look at our improved version:

function getRecursive(nr) {
  console.log(nr);
  if (nr > 0) {
    getRecursive(--nr);
  }
}
getRecursive(3);

This function is going to call itself until the value of the parameter is no longer bigger than 0. And then it stops.

What happens when we call a function recursively is that it goes one function deeper every time. The first function call is done last. For this function it goes like this:

• getRecursive(3)
  • getRecursive(2)
    • getRecursive(1) ...