es6-private-methods-with-symbols.js

const privateMethod = Symbol('privateMethod');

export default class Service {
  constructor () {
    this.say = "Hello";
  }
  
  [privateMethod] () {
    console.log(this.say);
  }
  
  publicMethod () {
    this[privateMethod]()
  }
}

// Uncaught TypeError: (intermediate value).privateMethod is not a function
new Service().privateMethod()

// Uncaught TypeError: (intermediate value)[Symbol(...)] is not a function
new Service()[Symbol('privateMethod')]();