// private fields must start with '#'
// and they can't be accessed outside the class block

class Counter {
  #x = 0;

  #increment() {
    this.#x++;
  }

  onClick() {
    this.#increment();
  }

}

const c = new Counter();
c.onClick(); // works fine
c.#increment(); // error

const stop = please && please.make && please.make.it && please.make.it.stop;

// or use a library like 'object-path'
const stop = objectPath.get(please, "make.it.stop");

const stop = please?.make?.it?.stop;

const duration = input.duration || 500;

const duration = input.duration ?? 500;

// can define BigInt by appending 'n' to a number literal
const theBiggestInt = 9007199254740991n;

// using the constructor with a literal
const alsoHuge = BigInt(9007199254740991);

// or with a string
const hugeButString = BigInt('9007199254740991');

1n < 2 
// true

1n + 2
// 🤷‍♀️ Uncaught TypeError: Cannot mix BigInt and other types, use explicit conversions

class Colors {
  // public static fields
  static red = '#ff0000';
  static green = '#00ff00';

  // private static fields
  static #secretColor = '#f0f0f0';

}


font.color = Colors.red;

font.color = Colors.#secretColor; // Error

// db.mjs
export const connection = await createConnection();

// server.mjs
import { connection } from './db.mjs';

server.start();

const cache = new Map();

const setValue =  (key, obj) => {
  cache.set(key, new WeakRef(obj));
};

const getValue = (key) => {
  const ref = cache.get(key);
  if (ref) {
    return ref.deref();
  }
};

// this will look for the value in the cache
// and recalculate if it's missing
const fibonacciCached = (number) => {
  const cached = getValue(number);
  if (cached) return cached;
  const sum = calculateFibonacci(number);
  setValue(number, sum);
  return sum;
};