Objects concatenation with redondant values.

Object_concatenation.js

let obj1, obj2, obj3;

/**
 * spread_synthax
 */
//with non redondant values, everyone stay
obj1 = { food: 'pizza', car: 'ford' };
obj2 = { animal: 'dog' };
obj3 = { ...obj1, ...obj2 };
console.log(obj3); // => { food: "pizza", car: "ford", animal: "dog" }

//with redondant values, the last stays
obj1 = { food: 'pizza', car: 'ford', animal: 'human' };
obj2 = { animal: 'dog' };
obj3 = { ...obj1, ...obj2 };
console.log(obj3); // => { food: "pizza", car: "ford", animal: "dog" }