Object.entries() but objects instead of array

Question

Say I have an object:

var obj = { a:{}, b:1, c: new Set() };

Objects are not iterable without work and Object.keys/values/entries are not quite what I want. Object.entries() is close, but I would prefer it returns an array of objects instead of a 2D array, ideally with references intact (where appropriate).

So something like:

Object.items( obj ) = [ { a: {} }, { b: 1 }, { c: new Set() } ];

I understand I could create a function to do this using Object.entries(), I just want to confirm that there isn't already something similar.

One-property objects make not much sense and are hard to deal with. What do you need this weird format for? No, there is indeed nothing in the standard lib that does this. — Bergi
– Bergi, Commented Mar 1, 2018 at 16:46
@Bergi Presumably he means that the {} value of a should be the same object in the result. Which is hard to avoid unless you go to extra lengths to make a copy. — Barmar
– Barmar, Commented Mar 1, 2018 at 16:48
But if he thinks that changing the value 1 of b in the original will propagate to the result (or vice versa) that can't be done. — Barmar
– Barmar, Commented Mar 1, 2018 at 16:49
@Barmar Well {get [key]() { return orig[key]; }, set [key](v) { orig[key] = v; }} could do even that :-) — Bergi
– Bergi, Commented Mar 1, 2018 at 16:50

Quentin · Accepted Answer · 2018-03-01 16:49:58Z

5

You are correct, there is nothing built it that does this. You would need to build your own function and entries is a good starting point.

var obj = { a:{}, b:1, c: new Set() };
var obj2 = Object.entries(obj).map((array) => ({ [array[0]]: array[1] }));

console.log(obj2);
console.log(obj2[2].c === obj.c);

answered Mar 1, 2018 at 16:49

Quentin

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1 Comment

Barmar Over a year ago

You can also use destructuring to get rid of [0] and [1].

Nina Scholz · Accepted Answer · 2018-03-01 17:00:37Z

0

You could define Symbol.iterator for the object and take single objects with just one property.

var obj = { a:{}, b:1, c: new Set() },
    array;
    
obj[Symbol.iterator] = function* () {
    for (var [key, value] of Object.entries(this)) {
        yield { [key]: value };
    }
};

array = Array.from(obj);

console.log(array);
console.log(array[2].c === obj.c);

answered Mar 1, 2018 at 17:00

Nina Scholz

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