JSFiddle - React, Tailwind, and code Playground

by Angelos Chaidas

HTML

<script src="https://wzrd.in/standalone/expect@latest"></script>
<script src="https://wzrd.in/standalone/deep-freeze@latest"></script>

Babel + JSX

// https://egghead.io/lessons/javascript-redux-avoiding-array-mutations-with-concat-slice-and-spread
const addCounter = (list) => {
	list.push(0);
	return list;
};

const testAddCounter = () => {
    const listBefore = [];
    const listAfter = [0];
	
	deepFreeze(listBefore);
	
    expect(addCounter(listBefore)).toEqual(listAfter);
}

testAddCounter();
console.log('All tests passed');