understand_prototype.js

/**
 * prototype is just way of saying for this object use other object
 * as a backup/delegate/prototype
 * if someone call my object with a property that doesn't exist on my object
 * go lookin this other object
 */

function talk() {
    console.log(this.sound)
}
let animal = {
    talk
}
let dog = {
    sound: 'woof'
}
let scoobyDoo = {
    howl: function() {
        console.log(this.sound.toUpperCase())
    }
}

Object.setPrototypeOf(dog, animal)
Object.setPrototypeOf(scoobyDoo, cat)

dog.talk() // woof
scoobyDoo.howl() // WOOF