ChaoticRoman/js-playground

JS Playground

My JavaScript playground for CodeWars katas with JavaScript.

Dependencies

Install node.js using nvm.

It sould look like

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.5/install.sh | bash
source ~/.bashrc

Then check for the latest versions

nvm ls-remote | grep LTS | tail -n 10

Install and set e.g. LTS v20:

nvm install 20
nvm use 20

Testing boilerplate

Provide quick boilerplate to test javascript function. More than once occurrence of a character in string function as a tested function, few tests and how to run it.

Here is a simple boilerplate to test a JavaScript function using Node.js and Jest testing framework.

First, install Jest using npm (Node Package Manager):

npm install --save-dev jest

Then, create a file named stringUtils.js for the function to be tested:

function moreThanOnceOccurrence(str, char) {
    let count = 0;
    for(let i = 0; i < str.length; i++) {
        if(str[i] === char) count++;
    }
    return count > 1;
}

module.exports = moreThanOnceOccurrence;

Next, create a test file named stringUtils.test.js:

const moreThanOnceOccurrence = require('./stringUtils');

test('moreThanOnceOccurrence function exists', () => {
    expect(typeof moreThanOnceOccurrence).toEqual('function');
});

test('character "a" occurs more than once in "banana"', () => {
    expect(moreThanOnceOccurrence('banana', 'a')).toBeTruthy();
});

test('character "b" does not occur more than once in "banana"', () => {
    expect(moreThanOnceOccurrence('banana', 'b')).toBeFalsy();
});

To run the tests, add the following to your package.json:

"scripts": {
    "test": "jest"
}

Then, you can run your tests using npm:

npm run test

This will run the Jest test runner on your test suite, and you'll see output for each of your tests.