How to check if array is multidimensional? (jQuery)

Question

I have two arrays of AJAX (JSON) response:

One dimension:

[["fili","Chif"],["Bart","deme"],["Bomb","Jyui"],["Joiu","FDPi"],["Doen","abcd"],["drog","MAIC"],["Jasi"
,"abcd"],["Jere","Jibi"]]

Three dimensions:

[[["5","#"],["2","N"],["L","7"],["C","8"],["F","W"],["K","T"],["Q","E"],["Z","\/"]],[["B","O"],["$","P"
],["1","Y"],["H","R"],["3","%"],["I","U"],["M","4"],["A","9"]],[["J","X"],["Bye","G"],["D","V"],["Bye"
,"6"]]]

I try to check if an array is multidimensional but does not work:

if (typeof arr[0][0] != "undefined" && arr[0][0].constructor == Array) {
     return true;
}

possible duplicate of How to check if a multidimensional array item is set in JS? — Oliver Gondža
– Oliver Gondža, Commented Jun 28, 2015 at 21:40
Never use == or != in Javascript. They're totally broken... go for === and !== instead. — 6502
– 6502, Commented Jun 28, 2015 at 21:57

bugwheels94 · Accepted Answer · 2015-06-29 07:35:52Z

22

You need to check the first element of Array so use

if(arr[0].constructor === Array)

DEMO

alert("[[]] returns " + ([[]].constructor === Array))

edited Jun 29, 2015 at 7:35

answered Jun 28, 2015 at 21:22

bugwheels94

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1 Comment

FBN Over a year ago

It worked when i changed to if(arr[0][0].constructor == Array) Thanks!

Stanislav Padimanskas · Accepted Answer · 2019-03-29 11:57:09Z

11

You can also check all elements in the array so I think it would be more right way in 2019

const is2dArray = array =>  array.every(item => Array.isArray(item));

answered Mar 29, 2019 at 11:57

Stanislav Padimanskas

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3 Comments

vsync Over a year ago

You surely mean some and not every dear sire. Also stating an arbitrary year in the answer is meaningless

bugwheels94 Over a year ago

@vsync since JS aint static typed, checking for multi dimensionality is always going to be dependent upon the type of input that might be provided to the function. Fortunately and mostly, we know the type of input that our function might encounter. Since, the question gives the input so all answers here are correct and checking first element is fastest. Plus, from question it looks like he would want every if he wants and not some otherwise his code might still fail

vsync Over a year ago

@bugwheels94 - it's a matter of the definition of what is a multidimensional array. Should all items be an Array or is it enough that one is. Also depends on the situation, and in OP's situation, it seems some would work better.

JohnP2 · Accepted Answer · 2017-02-20 18:36:49Z

4

If you like my answer, please vote for the person above me, but here is the above answer reconstructed in function format:

function is2dArray(array){
    if(array[0] === undefined){
        return false;
    }else{
        return (array[0].constructor === Array);
    }
}

demo

edited Feb 20, 2017 at 18:36

answered Feb 18, 2017 at 16:45

JohnP2

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2 Comments

vsync Over a year ago

So, you're saying arrow functions are not "functions enough"...?

JohnP2 Over a year ago

(oh that answer wasn't there when I responded. I mean the top answer)

Tim · Accepted Answer · 2019-12-10 11:31:00Z

0

Instead of using the constructor property, you may also use instanceof:

var arr = [];
var obj = {};

(arr instanceof Object)
// -> true

(obj instanceof Object)
// -> true

(arr instanceof Array)
// -> true

(obj instanceof Array)
// -> false

answered Dec 10, 2019 at 11:31

Tim

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Comments

Shibhe Tepa · Accepted Answer · 2018-11-30 07:08:43Z

-1

if(array[0][0] === undefined){
    return true;
}else{
    return false;
}

this one checks if the Array is a multi or just a normal array.

answered Nov 30, 2018 at 7:08

Shibhe Tepa

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1 Comment

vsync Over a year ago

This only works if you're lucky enough to have the very first item as an array itself.

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