Javascript Classes: es5 versus es6

javascriptClasses_es6_versus_es5.js

//old school es5 syntax for creating a class
//advantage: lets you create private functions and state through closure
//disadvantage: looks weird if you learned OO through language like c++/java/ruby, etc. Doesn't support prototypical inheritance.

//constructor function
function MyES5Class(aPrivateVar){
  var aontherPrivateVar = "I'm a private variable! You can't access me from the outside."  
  this.publicVar = "I'm a public variable! You can access me from the outside!"
  
  this.myPublicFunction = function(){
    //you can access private variables and functions in here (aPrivateVar, anotherPrivateVar, myPrivateFunction)
    console.log("I'm a public function! You can call me from the outside!")
  }  
  
  var myPrivateFunction = function(){
    console.log("I can only be called from within the instance. I'm private! I work through closure.")
  }
}

let myES5Object = new MyES5Class("my data")
myES5Object.myPublicFunction() // works
myES5Object.myPrivateFunction() // BLOWS UP! This throws an exception, as myPrivateFunction is hidden from the outside world through closure encapsulation.

//new es6 syntax
//advantage: looks familiar to people who have learned OO through languages like c++/java/ruby, etc. Supports prototypical inheritance. 
//disadvantage: doesn't allow for private fields or private methods. Boo!

class MyES6Class{
  constructor(someVar){
      this.someVar = someVar //you have to make these public :(
      this.publicVar = "I'm a public variable! You can access me from the outside!"
  }
  
  myPublicFunction(){
    console.log("I'm a public function! You can call me from the outside!")
  }
}

let myES6Object = new MyES6Class("my data")
myES6Object.myPublicFunction() // works
myES6Object.someVar            // works, since fields can't be made private in the new class syntax
myES6Object.publicVar          // works, since fields can't be made private in the new class syntax