2016-05-26-more-deeper-about-this-in-es6-arrow-function.exaple.js

class Person {
    constructor (firstName) {
        this.firstName = firstName;

        this.sayHiArrowFn = () => {
            console.log(this);
        }

        this.sayHiFn = function () {
            console.log(this);
        }
    }
}

const p1 = new Person('Shaun');

const sayHiArrowFn = p1.sayHiArrowFn;
sayHiArrowFn(); // Person { firstName: 'Shaun', sayHiArrowFn: [Function], sayHiFn: [Function] }

const sayHiFn = p1.sayHiFn;
sayHiFn(); // undefined