Quizze » Objekte

const obj = {
  true: 'a',
  ['true']: 'b',
  [true]: 'c',
};
const result = Object.keys(obj).length;

Was passiert?

const foo = 'bar';
const obj = {
  foo: 'a',
  [foo]: 'b',
};
const result = obj.foo;

Was passiert?

const foo = 'bar';
const obj = {
  foo: 'a',
  [foo]: 'b',
};
const result = obj.bar;

Was passiert?

const foo = 'bar';
const obj = {
  foo: 'a',
  [foo]: 'b',
};
const result = obj[foo];

Was passiert?

const foo = 'bar';
const obj = {
  foo: 'a',
  [foo]: 'b',
};
const result = obj[bar];

Was passiert?

const foo = 'bar';
const obj = {
  foo: 'a',
  [foo]: 'b',
};
const result = obj['foo'];

Was passiert?

const foo = 'bar';
const obj = {
  foo: 'a',
  [foo]: 'b',
};
const result = obj['bar'];

Was passiert?

const symbol1 = Symbol('symbol1');
const symbol2 = Symbol('symbol2');

const obj = {
  name1: 0,
  [symbol1]: 0,
};
Object.defineProperties(obj, {
  name2: { enumerable: false, value: 0 },
  [symbol2]: { enumerable: false, value: 0 },
});

const result = Object.keys(obj);

Was ist das Ergebnis?

const symbol1 = Symbol('symbol1');
const symbol2 = Symbol('symbol2');

const obj = {
  name1: 0,
  [symbol1]: 0,
};
Object.defineProperties(obj, {
  name2: { enumerable: false, value: 0 },
  [symbol2]: { enumerable: false, value: 0 },
});

const result = Reflect.ownKeys(obj);

Was ist das Ergebnis?

const symbol1 = Symbol('symbol1');
const symbol2 = Symbol('symbol2');

const obj = {
  name1: 0,
  [symbol1]: 0,
};
Object.defineProperties(obj, {
  name2: { enumerable: false, value: 0 },
  [symbol2]: { enumerable: false, value: 0 },
});

const result = Object.getOwnPropertyNames(obj);

Was ist das Ergebnis?

const symbol1 = Symbol('symbol1');
const symbol2 = Symbol('symbol2');

const obj = {
  name1: 0,
  [symbol1]: 0,
};
Object.defineProperties(obj, {
  name2: { enumerable: false, value: 0 },
  [symbol2]: { enumerable: false, value: 0 },
});

const result = Object.getOwnPropertySymbols(obj);

Was ist das Ergebnis?

const jane = {
  name: 'Jane',
  hello() {
    return `Hello ${this.name}!`;
  },
};
const func = jane.hello;

Welche dieser Möglichkeiten, obj.hello aufzurufen, funktionieren?

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

obj.prop = 'b';

Was ist proto.prop?

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

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

Was passiert?