es6.js

// -----------------------------
// export and import modules
// -----------------------------

// uno.js
const uno = {
    value: 1
}
export default uno
// ---
import first from './uno.js'

// duo.js
const one = {
    value: 1
}
const two = {
    value: 2
}
export const one
export const two

// импортировать жестко по имени
import { one } from './duo.js'
import { two } from './duo.js'

// импортировать как alias
// ---
import { one as Primo } from './duo.js'
import { two as Secondo } from './duo.js'

// все экспортируемые из файла duo.js константы преобразуются в свойтсва объекта bundle 
import * as bundle from './duo.js'
// =>
bundle {
    one: one
    two: two
}

// ----------------------
// es6
// ----------------------
class Human {
  
  constructor () {
    this.gender = 'male'
  }
  
  printGender () {
    console.log(this.gender)
  }
  
}

class Person extends Human {
  
  constructor () {
    super()
    this.name = 'Max'
  }
  
  printName () {
    console.log(this.name)
  }
  
}

// ---
const person = new Person()
person.printName();
person.printGender();


// ---------------------------
// es7
// ---------------------------
class Human {
  
  gender = 'male'
  
  printGender = () => {
    console.log(this.gender)
  }
  
}

class Person extends Human {
  
  name = 'Max'
  
  printName = () => {
    console.log(this.name)
  }
  
}

// ---
const person = new Person()
person.printName();
person.printGender();