How to copy an object or array

Objects and Array

var player = {score: 1, name: 'Jeff'};

var newPlayer = Object.assign({}, player, {score: 2});
// Now player is unchanged, but newPlayer is {score: 2, name: 'Jeff'}

// Or if you are using object spread syntax proposal, you can write:
var newPlayer = {...player, score: 2};

// for Arrays
var player = ['Ronaldo', 'Merci', 'Rooney']
var newPlayer = player.slice()
newPlayer.push('Jeff')