Make a JavaScript Object Iterable

makeObjIterable.js

const makeIterable = obj => Object.defineProperty(obj, Symbol.iterator, {
  writable: true,
  value: function*() {
    const values = Object.values(obj);
    for (let value of values) {
      yield value;
    }
  },
});

const obj = makeIterable({
  a: 1,
  b: 2,
  c: 3,
});

// now JavaScript constructs that make use of the iteration protocol can be used with obj:

// for..of
for (let value of obj) {
  console.log(value);
}
// 1
// 2
// 3

// destructuring assignment
[a, b, c] = obj;
console.log(c); // 3

// spread syntax
const arr = [...obj];
console.log(arr); // [1, 2, 3]

// using Object.defineProperty, the enumerable property defaults to false; therefore, Symbol.iterator won't show up when logging obj:
console.log(obj); // {a: 1, b: 2, c: 3}

// set Symbol.iterator using normal assignment or set enumerable to true and you'll get:
console.log(obj); /*
{
  a: 1,
  b: 2,
  c: 3,
  [Symbol(Symbol.iterator)]: [GeneratorFunction]
}
*/