How to check if there is at least one element in a multidimensional array? (Silly Basic Javascript Questionn)

Question

How to check if there is at least one element in an array? (I want to verify if the array is not empty.)

Sorry for this silly question, I already spent too much time on Google... (Google only returns complex situations and solutions. It seems like my question is too simple.).

EDIT: Ok, but what will happen with an array like [,,[],,[],,,] ? For my purposes, it should be considered as empty.

EDIT 2: Sorry, guys, for the confusion! At first, I didn't even know exactly what I was looking for. Thank you all!

Use the array length property. If it is greater than 0 it has an element — Anand Sunderraman, Sep 21 '16 at 00:44
Possible duplicate of [Check if array is empty or exists](http://stackoverflow.com/questions/11743392/check-if-array-is-empty-or-exists) — user2005218, Sep 21 '16 at 00:47
`array.length > 0 && array[0].length > 0` (repeat for as many dimensions as you have) — Bergi, Sep 21 '16 at 00:53
How come you have the `multidimensional-array` tag? Can you give an example of the structure of your array? — qxz, Sep 21 '16 at 01:09
@qxz I might get something like that: arr = [,,[],,[],,,] For my purposes [,,[],,[],,,] is empty, while [,,["a"],,[],,,] is not. — Emilio, Sep 21 '16 at 02:39

score 1 · Accepted Answer · answered Sep 21 '16 at 02:49

1

This would fulfill your new requirements:

function isEmpty(arr) {
    if (!Array.isArray(arr)) {
        return false;
    }

    return arr.every(isEmpty);
}

What it does: with the help of Array.prototype.every it checks that the every item left is an empty array. And the array holes are automatically skipped by .every().

References:

answered Sep 21 '16 at 02:49

zerkms

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This would only work for a second dimension, right? Any clue on how to reach the third, fourth or fifth dimension? – Emilio Sep 21 '16 at 02:54
@Emilio it is recursive and would work with any depth. `isEmpty([,,,[[],[],,,,[[[]]]],,,]) // true` – zerkms Sep 21 '16 at 02:54

score -1 · Answer 2 · answered Sep 21 '16 at 01:04

-1

You could also use truthiness here. This would help you check against undefined at the same time. [] is falsy, so you could do this:

var arr = [];

if(!arr) {
  ... arr is undefined or empty array
} else {
  ... arr has at least one value
}

answered Sep 21 '16 at 01:04

brandon-barnett

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Wrong, `[]` is truthy. Try it in your browser console. – qxz Sep 21 '16 at 01:07
That's just not true.. `[]` is true, `[1]` is too – dmonad Sep 21 '16 at 01:07
Odd: [] == true is false – brandon-barnett Sep 21 '16 at 01:17
@user3191461 in JS being "truthy" does not mean "equal to `true`" – zerkms Sep 21 '16 at 02:44

How to check if there is at least one element in a multidimensional array? (Silly Basic Javascript Questionn)

2 Answers2