I shipped skillcraft.ai !!!
Skillcraft helps you find the best learning resources tailored to your goals. Get a personalized roadmap with the best courses, books, and tutorials. Try it out, for free!
Up to date
Published
4 min read

Trevor I. Lasn

Building tools for developers. Currently building skillcraft.ai and blamesteve.lol

Recursion Explained In Simple Terms

Understanding recursion through real examples - why functions call themselves and when to use them

Most tutorials explain recursion using factorials or Fibonacci sequences. That’s nice for learning, but you won’t use those in real work. Let’s look at recursion through actual code you might write.

Think of recursion like reading through a thread of Slack comments. You see a message with replies, and those replies have their own replies, and it keeps going deeper. Each level of replies is the same thing - just messages and responses - but each level is dealing with a smaller piece of the conversation.

In programming, recursion works the same way. A function calls itself to handle a smaller version of the same task. Here’s a Slack comment system to see how recursion works.


This code would output:

That’s all recursion is - a function that calls itself to handle smaller pieces of data. In our example, it’s showing a comment, then showing all its replies, then their replies, and so on.

Every recursive function needs two crucial parts:

  1. Something it’s trying to do (like displaying a comment)
  2. A “base case” that tells it when to stop (when there are no more replies)

Think of it like this: if someone asks you to count all the comments in a Slack thread, you might say “Okay, I’ll count this comment (1), then count all the replies, then count their replies…” That’s recursion - breaking down a big task into smaller, similar tasks.

File Explorers and Directory Trees

The most common place you’ll use recursion is when dealing with files and folders. Think about Windows Explorer or Finder on Mac. They both need to show you files inside folders, which can have more folders inside them, and more folders inside those… you get the idea.

This function looks in a folder. If it finds a file, it adds it to the list. If it finds another folder, it looks inside that one too.

A Store Category Menu

The category menu in an online store works just like nested folders. Electronics contains Computers, which contains Laptops. Each category can hold more categories inside it.

Running this code shows:

The showCategories function looks at each category and then peers inside it for more categories.

It starts at “Store” and prints it. Inside Store it finds “Electronics”, prints that with some space to show it’s inside Store. This pattern continues - looking inside each category and printing what it finds - until it hits empty categories. The spaces at the start of each line show how deep the category sits in the menu.

Essentially, recursion is just a way to handle nested data - like comments with replies, or folders with more folders inside. Don’t overcomplicate it. If you can break down your problem into smaller, similar problems, recursion might be the right tool for the job.


Found this article helpful? You might enjoy my free newsletter. I share dev tips and insights to help you grow your coding skills and advance your tech career.


Check out these related articles that might be useful for you. They cover similar topics and provide additional insights.

Tech
5 min read

The Fight to Free JavaScript from Oracle's Control

The creator of JavaScript and Node.js are challenging Oracle's control over the JavaScript name

Nov 23, 2024
Read article
Tech
4 min read

No, Quantum Computers Won't Break All Encryption

Symmetric encryption algorithms like Advanced Encryption Standard (AES) are largely quantum-resistant already

Oct 31, 2024
Read article
Tech
5 min read

VoidZero: Threat or Catalyst for Open Source JavaScript Tooling?

When Evan You announced VoidZero, I'll admit - I got excited. And a little nervous.

Oct 15, 2024
Read article
Tech
3 min read

The Crutch Effect: How AI Tools Became A Crutch

Introducing The Crutch Effect

Sep 13, 2024
Read article
Tech
3 min read

Introducing courses.reviews

Cutting through the noise of thousands of online courses to find the ones actually worth your time

Jun 2, 2025
Read article
Tech
8 min read

Apple's Secret Sauce: The Untold Stories Behind Its Success

Diving deep into the lesser-known factors that propelled Apple from a garage startup to a tech titan

Sep 30, 2024
Read article
Tech
3 min read

Honey Quietly Hijacked Creator Revenue Through Affiliate Link Switching

Honey's controversial affiliate link practices and what it teaches us about Silicon Valley's ethics

Jan 4, 2025
Read article
Tech
3 min read

The Credit Vacuum

Being a developer sometimes feels like being the goalkeeper in a soccer match. You make a hundred great saves, and no one bats an eye. But let one ball slip through, and suddenly you're the village idiot.

Oct 7, 2024
Read article
Tech
3 min read

You Don't Own Your Social Media Accounts

Social platforms promise exposure but quietly hold your audience hostage

Nov 28, 2024
Read article

This article was originally published on https://www.trevorlasn.com/blog/recursion-explained. It was written by a human and polished using grammar tools for clarity.