Is it possible to get the non-enumerable inherited property names of an object?

Question

In JavaScript we have a few ways of getting the properties of an object, depending on what we want to get.

1) Object.keys(), which returns all own, enu

Answer 1

Straight forward iterative in ES6:

function getAllPropertyNames(obj) {
    let result = new Set();
    while (obj) {
        Object.getOwnPropertyNames(obj).forEach(p => result.add(p));
        obj = Object.getPrototypeOf(obj);
    }
    return [...result];
}

Example run:

function getAllPropertyNames(obj) {
  let result = new Set();
  while (obj) {
    Object.getOwnPropertyNames(obj).forEach(p => result.add(p));
    obj = Object.getPrototypeOf(obj);
  }
  return [...result];
}

let obj = {
  abc: 123,
  xyz: 1.234,
  foobar: "hello"
};

console.log(getAllPropertyNames(obj));

Answer 2

Taking advantage of Sets leads to a somewhat cleaner solution, IMO.

const own = Object.getOwnPropertyNames;
const proto = Object.getPrototypeOf;

function getAllPropertyNames(obj) {
    const props = new Set();
    do own(obj).forEach(p => props.add(p)); while (obj = proto(obj));
    return Array.from(props);
}

Answer 3

if you are trying to log non enumerable properties of a parent object ex. by default the methods defined inside a class in es6 are set on prototype but are set as non-enumerable.

Object.getOwnPropertyNames(Object.getPrototypeOf(obj));