Advanced function concepts

Pure functions & Side Effects

function add(num1, num2) {
    return num1 + num2;
}

console.log(add(1,5)); // 6
console.log(add(12,12)); // 24

Side effect example:

let previousResult = 0;

function addMoreNumbers(num1, num2) {
    const sum = num1 + num2;
    previousResult = sum; // Here we have the side effect
    return sum;
}

console.log(addMoreNumbers(1,2));

Another example can be:

const hobbies = ['Sports', 'Cooking'];
function printHobbies(h) {
    h.push('NEW HOBBY'); // Side effect here
    console.log(h);
}
printHobbies(hobbies);