JSFiddle - React, Tailwind, and code Playground

JavaScript

var numbers = [1, 2, 4, 6, 8];

numbers = square(numbers);

assertResult(numbers);

/**
 * Squares all numbers in the array and return resutls as array
 * @param {array} numbers
 * @return {array}
 */
function square(numbers) {
    /* TODO: implement function */ 
    return numbers.map(function (number) {
        return number * number;
    });
}

//NOTES: 
// you can use lo-dash (aka underscore) library 












// assertions

function assertResult (numbers) {
    if (_.isEqual(numbers, [1, 4, 16, 36, 64])) {
        alert("SUCCESS!");
    } else { 
        alert("FAILURE");
    }
}