class.js

"use strict"

class C {
  constructor() {
    this.x = 1
  }
  say(str) {
    console.log(str)
  }
  static static() {
    console.log(this)
  }
}

console.log(C.prototype) // => { say: [Function] }
console.log(C.prototype.constructor === C) // => true

let a = new C
a.say('hi') // => hi
C.prototype.say = () => console.log('wow')
a.say('hi') // => wow

class D extends C {
  sup() {
    console.log(super.constructor === C) // => true
    super.say('yoyoyo') // => wow
  }
}

console.log(D.prototype.constructor === D) // => true
console.log(D.prototype.say == C.prototype.say) // => true
console.log(C.isPrototypeOf(D)) // => true
let b = new D
b.sup()

class E extends function() {
  console.log('test')
} {
  get a() {
    return 1
  }
  *generator () {
    yield 2
  }
  static set b(param) {
    console.log('set b to ' + param)
  }
}
a = new E // => test
console.log(a.a) // => 1
console.log(a.generator().next().value) // => 2
console.log(E.name) // => E
E.b = 1 // => set b to 1

try {
  class F {
    static name() { }
  }
} catch (e) {
  console.log(e) // => [TypeError: Cannot redefine property: name]
}

class G extends Array {
  constructor() {
    return super(1, 2)
    // new super() // => error in traceur
  }
}
console.log(new G) // => [ 1, 2 ]