JSFiddle - React, Tailwind, and code Playground

JavaScript

const originalArray = [1, 'a', false, {foor: 'bar'}]
const newArray = [];

originalArray.forEach((v, i) => {
	newArray.push(originalArray[i]);
});

newArray[0] = newArray[0] + 1;
newArray[1] = 'b';
newArray[2] = true;
newArray[3] = Object.assign(newArray[3], {bar: 'foo'});

console.log('original: %o', originalArray);
console.log('new: %o', newArray);