JS: Reflect.getOwnPropertyDescriptor

New in JS2015.

Reflect.getOwnPropertyDescriptor(obj, key)

• Return the Property Attributes in the form of Property Descriptor.
• If the property doesn't exist, returns undefined.
• If obj is not object, throw a TypeError exception.

const jj = { p: 4 };

console.log(
  JSON.stringify(Reflect.getOwnPropertyDescriptor(jj, "p")) ===
    '{"value":4,"writable":true,"enumerable":true,"configurable":true}',
);

// non-exist key
console.log(
  Reflect.getOwnPropertyDescriptor(jj, "yy") === undefined,
);