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JavaScript Katas: Split In Parts

August, 2020

Intro 🌐

Problem solving is an important skill, for your career and your life in general.

That’s why I take interesting katas of all levels, customize them and explain how to solve them.

Understanding the Exercise❗

First, we need to understand the exercise! If you don’t understand it, you can’t solve it!.

My personal method:

  1. Input: What do I put in?
  2. Output: What do I want to get out?

Today’s exercise

Today, another 7 kyu kata, meaning we slightly increase the difficulty.

Source: Codewars

Write a function splitInParts, that accepts two parameters: myString and partLength.

Given a string, e.g. "HelloDev", and a number, e.g. 3, return the input string split into partLength-long parts separated by a space, e.g. Hel loD ev.

Input: a string and a number.

Output: a string.

Thinking about the Solution 💭

I think I understand the exercise (= what I put into the function and what I want to get out of it).

Now, I need the specific steps to get from input to output.

I try to do this in small baby steps:

  1. Get a partLength-long part of the input string and add a space
  2. Do this for every part
  3. Add the remaining part to the end
  4. Return the string


  • Input: "HelloDev", 3
  • Get a 3-long part of the input string and add a space: "Hel "
  • Get a 3-long part of the input string and add a space: "loD "
  • Add the remaining part to the end: "ev"
  • Return the string: "Hel loD ev"
  • Output: "Hel loD ev"

Implementation ⛑

function splitInParts(myString, partLength) {
  let remaining = myString;
  let result = "";

  // do it only if the remaining string is longer than the parts
  while (remaining.length >= partLength) {
    // add the next part and a space to the result
    result += remaining.slice(0, partLength) + " ";

    // remove the added part from the remaining string
    remaining = remaining.slice(partLength);

  // add the last part that was smaller than the part length
  result += remaining;

  // remove a trailing space
  return result.trim();


console.log(splitInParts("HelloDev", 3));
// "Hel loD ev" ✅

console.log(splitInParts("HelloDev", 1));
// "H e l l o D e v" ✅

Playground ⚽

You can play around with the code here

Next Part ➡️

Great work!

We learned how to use while, slice, trim.

I hope you can use your new learnings to solve problems more easily!

Next time, we’ll solve another interesting kata. Stay tuned!

If I should solve a specific kata, shoot me a message here.

If you want to read my latest stuff, get in touch with me!

Further Reading 📖

Questions ❔

  • How often do you do katas?
  • Which implementation do you like more? Why?
  • Any alternative solution?


Hi! I'm Michael 👋 I'm a Mentor & Educator & Senior Web Developer - I help you to reach your (career) goals.