Composition

• Composition can be used for code reuse
• Favor composition over inheritance.
• With composition, instead of having the complex hierarchy, you can compose a few objects together to create a new object. and this technique gives you great flexibility.

const walkable = {
    walk: function() {
        console.log("walking");
    }
}

const eatable = {
    eat: function() {
        console.log("eating");
    }
}

const swimmable = {
    swim: function() {
        console.log("swimming");
    }
}

Using with simple objects

const person = Object.assign({}, walkable, eatable);

Using with Prototype

function Person() {}

Object.assign(Person.prototype, walkable, eatable);

Using with mixin

// using mixin
function mixin(target, ...sources) {
    Object.assign(target, ...sources);
}

mixin(Person.prototype, walkable, eatable);