Why JSON.stringify() returns empty result for some objects

Question

This question is so basic, yet I have no idea of the answer.

Why screen object when stringified returns empty?

Does this mean JSON.stringify() needs read/write access to the input?

let a = {foo: 'one', bar: 2};


console.log(JSON.stringify(a));
console.log(JSON.stringify(screen));

@Variable https://developer.mozilla.org/en-US/docs/Web/API/Window/screen . If it was never declared you'd get an error about it being undefined. — ADyson, Jul 27 '18 at 11:10
Possible duplicate of [Stringify DOMWindow object](https://stackoverflow.com/questions/4079653/stringify-domwindow-object) — user202729, Jul 27 '18 at 11:11
@ADyson Thanks, didn't knew about this, learned something new :D. — node_modules, Jul 27 '18 at 11:17
@user202729 I think the answer here is better than the one in the duplicate. I'll change the tittle so that it's more general. — Lemures, Jul 27 '18 at 11:29

score 11 · Accepted Answer · edited Oct 17 '18 at 05:42

11

FROM MDN Network

For all the other Object instances (including Map, Set, WeakMap and WeakSet), only their enumerable properties will be serialized.

Read https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify

    console.log((window.screen));
    console.log(JSON.stringify(window.screen));
    console.log(window.propertyIsEnumerable(screen));

edited Oct 17 '18 at 05:42

Skeets

answered Jul 27 '18 at 11:25

Kapil Tiwari

3

Actually, most of the (popular) answers on this site are just a docs-quote. That is a proper answer (as long as you quote important parts and not just a link) – user202729 Jul 27 '18 at 12:56

1 Answers1