let getPrice = (d, n) => {return {price: d+n};};
let toppings = ['onions', 'tomato', 'lettuc', 'pickle'];
let defaultFoodItem = {sauce: 'mild', hasCreameSause: 'yes', price: 2.34, toppings: [...toppings]};
let taco = Object.assign({}, defaultFoodItem, {food: 'taco'}, getPrice(defaultFoodItem.price, 1.45));
let fancyTaco = Object.assign({}, taco,
                Object.assign({}, {toppings: [...toppings, 'cheese', 'special sauce', 'vinegrate']}),
                              getPrice(taco.price, 2.25)
                             );

console.log('defaultFoodItem', defaultFoodItem);
console.log('taco', taco);
console.log('fancyTaco', fancyTaco);

/* Console:
defaultFoodItem Object {sauce: "mild", hasCreameSause: "yes", price: 2.34, toppings: Array[4]}
taco Object {sauce: "mild", hasCreameSause: "yes", price: 3.79, toppings: Array[4], food: "taco"}
fancyTaco Object {sauce: "mild", hasCreameSause: "yes", price: 6.04, toppings: Array[7], food: "taco"}
*/