indreklasn

class CustomDate {
  // ...
  static epoch = new CustomDate(0);
}

/* or */

class CustomDate {
  // ...
}

indreklasn

const x = Number.MAX_SAFE_INTEGER;
// ↪ 9007199254740991, this is 1 less than 2^53

const y = x + 1;
// ↪ 9007199254740992, ok, checks out

const z = x + 2
// ↪ 9007199254740992, wait, that’s the same as above!

indreklasn

const theBiggestInt = 9007199254740991n;

const alsoHuge = BigInt(9007199254740991);
// ↪ 9007199254740991n

const hugeButString = BigInt('9007199254740991');
// ↪ 9007199254740991n

indreklasn

const x = Number.MAX_SAFE_INTEGER;
// ↪ 9007199254740991, this is 1 less than 2^53

const y = x + 1;
// ↪ 9007199254740992, ok, checks out

const z = x + 2
// ↪ 9007199254740992, wait, that’s the same as above!

indreklasn

const response = {
  settings: {
    nullValue: null,
    height: 400,
    animationDuration: 0,
    headerText: '',
    showSplashScreen: false
  }
};

indreklasn

// Potentially unintended. '' is falsy, result: 'Hello, world!'
const headerText = response.settings.headerText || 'Hello, world!'; 

// Potentially unintended. 0 is falsy, result: 300
const animationDuration = response.settings.animationDuration || 300; 

// Potentially unintended. false is falsy, result: true
const showSplashScreen = response.settings.showSplashScreen || true;

indreklasn

const response = {
  settings: {
    nullValue: null,
    height: 400,
    animationDuration: 0,
    headerText: '',
    showSplashScreen: false
  }
};

indreklasn

obj?.prop       // optional static property access
obj?.[expr]     // optional dynamic property access
func?.(...args) // optional function or method call

indreklasn

iterator.return?.() // manually close an iterator

indreklasn

data?.map(item => <div>{item}<div>