miku86

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JavaScript Katas: Repeat it

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

Source: Codewars

Write a function `repeatIt`, that accepts two parameters: `inputString` and `repetitions`.

Given a string, e.g. `"Hi"`,
and a number of repetitions, e.g. `2`,
return a string that repeats the input string n number of times, e.g. `"HiHi"`:

If the input is not a string, return "Not a string".

Input: a string and a number.

Output: a string.

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. Check if it is a string
2. If yes, then repeat it x times

Example:

• Input: `"Hi", 2`
• Check if it is a string: `true`
• Iteration 1: add it to results => `"Hi"`
• Iteration 2: add it to results => `"HiHi"`
• Output: `"HiHi"`

Implementation (native method) ⛑

``````function repeatIt(inputString, repetitions) {
// check if it is a string
if (typeof inputString !== "string") {
return "Not a string";
}

// repeat it x times
return inputString.repeat(repetitions);
}
``````

Result

``````console.log(repeatIt("Hi", 2));
// "HiHi" ✅

console.log(repeatIt(999, 1));
// "Not a string" ✅
``````

Implementation (for loop) ⛑

``````function repeatIt(inputString, repetitions) {
// check if it is a string
if(typeof inputString !== "string"){
return "Not a string";
}

// variable for result
let result = "";

// repeat it x times
for(let i = 0; i < repetitions; i++){
result += inputString
}

return result;
}
``````

Result

``````console.log(repeatIt("Hi", 2));
// "HiHi" ✅

console.log(repeatIt(999, 1));
// "Not a string" ✅
``````

Playground ⚽

You can play around with the code here

Next Part ➡️

Great work!

We learned how to use `typeof`, `repeat` and `for`.

I hope that 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!

Questions ❔

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

``````const repeat = (word: string, n: number): string => {