A more refined Javascript typeof?

Question

Is there a way for typeof to return what an object is?

typeof {};

returns "object"

typeof [];

also returns "object". Is there a way in js to return "array"?

On top of that, is there a way to tell if an object is a DOM object, a javascript object or whatever object?

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/typeof Since everything is an object you have to play games to get further details. — Dave Newton, Feb 23 '16 at 19:56
See [`instanceof`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/instanceof) `[] instanceof Array` is `true` `({}) instanceof Array` is `false` This also applies to non-Array types. `document.body instanceof `[`Element`](https://developer.mozilla.org/en-US/docs/Web/API/Element) is `true` — arcyqwerty, Feb 23 '16 at 19:57
If you really need to write code that checks whether a variable is a DOM element or a JavaScript object, you should probably ask why you're getting both in the same function in the first place. — Blazemonger, Feb 23 '16 at 19:58
as @arcyqwerty mentioned, you can do it like in this fiddle: https://jsfiddle.net/gmjy3ybv/ — Icepickle, Feb 23 '16 at 20:06

score 5 · Accepted Answer · answered Feb 23 '16 at 19:57

5

You can't extend the typeof operator but for better type inspection you can (ab)use Object.prototype.toString

Object.prototype.toString.call([]) === '[object Array]'
Object.prototype.toString.call(document) === '[object HTMLDocument]`

answered Feb 23 '16 at 19:57

Mike Cluck

1

This is a really inefficient solution. You should use [the `instanceof` operator](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/instanceof). – Grant Gryczan Jun 09 '18 at 05:44
`instanceof` does not *return what an object is* so this is the only answer – Jun 22 '19 at 00:35

score 3 · Answer 2 · answered Feb 23 '16 at 19:55

3

You can use Array.isArray() for it.

The Array.isArray() method returns true if an object is an array, false if it is not.

answered Feb 23 '16 at 19:55

Nina Scholz

2 Answers2