# Will's Blog  # FizzBuzz: Writing and Testing the Classic Problem in JavaScript

In this tutorial, we will walk through solving the classic FizzBuzz problem in JavaScript. The code and testing procedures are part of my "EssentialAlgos" project available on GitHub.

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## What is FizzBuzz?

FizzBuzz is a programming challenge often used in coding interviews. The task is to print numbers from 1 to `n`, replacing multiples of 3 with "Fizz", multiples of 5 with "Buzz", and multiples of both 3 and 5 with "FizzBuzz".

## The Core FizzBuzz Function

Let's dive right into the code. The `fizzBuzz` function in JavaScript is as follows:

This is the third iteration of fizzbuzz I've completed with the suggestion of Ronald Zielaznicki on Linkedin at https://www.linkedin.com/in/ronaldziel/

``````// // fizzBuzzVersion3
let fizzbuzz = (int) => {
let arr = [];

for(let index = 1; index <= int; index++) {
if(index % 3 === 0 && index % 5 === 0) {
arr.push("FizzBuzz");
} else if (index % 3 === 0) {
arr.push("Fizz");
} else if (index % 5 === 0) {
arr.push("Buzz")
} else {
arr.push(`\${index}`)
}
}

return arr;
}
``````

I created another version with slight improvements over the last iteration.

``````// fizzBuzzVersion2
let fizzBuzz = (int) => {
let arr = [];

for(let index = 1; index <= int; index++){
let value = '';

if(index % 3 === 0){
value += "Fizz";
}

if(index % 5 === 0){
value += "Buzz";
}

if(!value){
value += `\${index}`;
}

arr.push(value);
}

return arr;
}
``````

To be transparent this was the original version I came up with before the refactored version above.

``````// originalFizzBuzz
let fizzBuzz = (int) => {
let arr = [];

for(let index = 1; index <= int; index++) {
if(index % 3 === 0 && index % 5 !== 0) {
arr.push("Fizz");
continue;
}

if(index % 5 === 0 && index % 3 !== 0){
arr.push("Buzz")
continue;
}

if(index % 5 === 0 && index % 3 === 0) {
arr.push("FizzBuzz");
continue;
}

arr.push(`\${index}`)
}

return arr;
}
``````

This function takes an integer `int` and returns an array containing the FizzBuzz sequence.

## Testing FizzBuzz with Jest

Testing is crucial for validating the correctness of your code. I have written Jest tests for this function.

``````const originalFizzBuzz = require("./fizzbuzz");
const fizzBuzzVersion2 = require("./fizzbuzz.v2/fizzbuzz.v2");
const fizzBuzzVersion3 = require("./fizzbuzz.v3/fizzbuzz.v3");

const checkReturnsEmptyArray = (func) => {
let arr = func();
expect(arr).toStrictEqual([]);
};

describe('FizzBuzz Tests', () => {
describe('Empty Array Tests', () => {
test.each([
[originalFizzBuzz, 'Returns an empty array when given no values'],
[fizzBuzzVersion2, 'Returns an empty array when given no values'],
[fizzBuzzVersion3, 'Returns an empty array when given no values']
])('%s', (func, description) => {
checkReturnsEmptyArray(func);
});
})

describe('Output for Input 3', () => {
test('Original version should return ["1", "2", "Fizz"] when given 3', () => {
const arr = originalFizzBuzz(3);
expect(arr).toStrictEqual(["1", "2", "Fizz"]);
});

test('Version 2 should return ["1", "2", "Fizz"] when given 3 for v2', () => {
const arr = fizzBuzzVersion2(3);
expect(arr).toStrictEqual(["1", "2", "Fizz"]);
});

test('Version 3 should return ["1", "2", "Fizz"] when given 3 for v2', () => {
const arr = fizzBuzzVersion3(3);
expect(arr).toStrictEqual(["1", "2", "Fizz"]);
});
});

describe('Output for Input 15', () => {
test('Original version should return the expected FizzBuzz sequence up to 15', () => {
const arr = originalFizzBuzz(15);
expect(arr).toStrictEqual(["1","2","Fizz","4","Buzz","Fizz","7","8","Fizz","Buzz","11","Fizz","13","14","FizzBuzz"]);
});

test('Version 2 should return the expected FizzBuzz sequence up to 15', () => {
const arr = fizzBuzzVersion2(15);
expect(arr).toStrictEqual(["1","2","Fizz","4","Buzz","Fizz","7","8","Fizz","Buzz","11","Fizz","13","14","FizzBuzz"]);
});

test('Version 3 should return the expected FizzBuzz sequence up to 15', () => {
const arr = fizzBuzzVersion2(15);
expect(arr).toStrictEqual(["1","2","Fizz","4","Buzz","Fizz","7","8","Fizz","Buzz","11","Fizz","13","14","FizzBuzz"]);
});
})

});
``````

This test ensures that when the function is provided an input, returns the right output.

## LeetCode Submission and GitHub Repository

You can find my FizzBuzz submission on LeetCode. The complete code and tests are available in my GitHub repository: EssentialAlgos.

## Conclusion

We have successfully tackled the FizzBuzz problem and validated its correctness through Jest testing. This exercise is a foundational problem but provides a valuable practice platform for budding coders and seasoned developers alike.

Feel free to connect with me for any questions or discussions on algorithms, coding, or potential opportunities: