immutable-push-method.md

const ships = ['X-wing', 'TIE Fighter', 'Millenium Falcon']

// define newShips with a spread of ships, creating a new reference
const newShips = [...ships, 'Destroyer']

// the original variable wasn't updated
console.log(ships)
// ['X-wing', 'TIE Fighter', 'Millenium Falcon']

// only the new one was updated
console.log(newShips)
// ['X-wing', 'TIE Fighter', 'Millenium Falcon', 'Destroyer']