(Ad, please don’t block.)

Quizzes » Prototype chains and classes

1. Prototype chains

const proto = { prop: 'a' };
const obj = Object.create(proto);

obj.prop = 'b';

What is proto.prop?

2. Prototype chains

const proto = {
  foo: 'p',
  logFoo() {
    console.log(this.foo);
  }
};
const obj = {
  foo: 'o',
  __proto__: proto,  
};

proto.logFoo.call(obj);
proto.logFoo.call(proto);

What happens?

3. Classes (1/3)

const result = typeof class extends Array {}

Result?

4. Classes (2/3)

const result = new Foo(3).length;
class Foo extends Array {}

What happens?

5. Classes (3/3)

class Foo extends Array {}
const result = new Foo(3).length;

What happens?


Correct answers: 0 out of 0