Recursion Explained Simply

Recursion is one of those things that you just don't get the first time.

It seems like a simple concept, but then you end up even more confused.

Don't worry, your not stupid. It is a confusing topic to begin with.

Without further ado, here's my take on the subject.

What is recursion?

There's this old joke about recursion:

To understand recursion, you must first understand recursion

When I first read this, my mind was blown because I didn't understand shit. But now whenever someone asks me "What is recursion?" I simply quote the joke because it is true.

Simply explained recursion is a method of solving problems by breaking them down into smaller problems, aka Divide and Conquer.

Lets imagine a scenario:

Problem: You ordered a whole pizza and you want to eat it all, but the pizza is just big to eat at once.

Solution: You break down the pizza into slices, then you can eat the slices piece by piece.

This is a very abstract example of recursion but I just want you to understand the concept of divide and conquer because at it's core recursion is a way of solving problems that uses divide and conquer.

Example

Let's layout the groundwork:

Problem: I want a function that takes a number and counts down from it:

Sample Input: 5

Sample Output:

5
4
3
2
1

You might say this can be simply done using a loop and your right, but in the context of this post this is a good example to showcase recursions.

function countDownFrom(number){
    if(number === 0){
     return; // base case
    }
    console.log(number)
    countDownNumber(number - 1); // recursive case 
}

Let's break this down every recursive function should have:

Base case: It's a condition that stops function, without it our functions will go on endlessly.

Recursive case: It's where you call the function again with different parameters.

Now we can give recursion a new definition:

Recursion is when a function calls itself, until it doesn’t.

Conclusion

I hope by the end of this you are less confused about recursion. If you got any questions leave them down in the comments.