JavaScript multidimensional-array check if typeof is 'undefined'

Question

If you create a multidimensional-array:

var ThisArray = [];
ThisArray["a"] = [];
ThisArray["a"]["b"] = [];
ThisArray["a"]["b"]["c"] = "This is a string.";

How can you check if ThisArray["a"]["w"]["c"] for example is defined. Right now I'm doing this:

if (typeof ThisArray !== 'undefined') {
    if (typeof ThisArray["a"] !== 'undefined') {
        if (typeof ThisArray["a"]["w"] !== 'undefined') {
            if (typeof ThisArray["a"]["w"]["c"] !== 'undefined') {

                // ThisArray["a"]["w"]["c"] is defined!

            }
        }
    }
}

How can I do this better and cleaner?

An array should have number indices, not strings. Did you mean to use an object {}? — elclanrs
– elclanrs, Commented Apr 7, 2021 at 20:04

Yoav Kadosh · Accepted Answer · 2021-04-07 20:09:57Z

4

Use optional chaining:

if (typeof ThisArray?.["a"]?.["w"]?.["c"] !== 'undefined') {
   // ThisArray["a"]["w"]["c"] is defined!
}

As noted in the comments, this is a relatively new language feature, and is not supported by older browsers. See Browser Compatibility.

edited Apr 7, 2021 at 20:09

answered Apr 7, 2021 at 20:06

Yoav Kadosh

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2 Comments

gen_Eric Over a year ago

Note that this requires Firefox 74+ or Chrome 80+

Tom O. Over a year ago

This is a great solution, just make sure this meets the browser compatibility requirement for your project: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

Ran Turner · Accepted Answer · 2021-04-07 20:10:51Z

0

You can use optional chaining. the optional chaining operator enables simple way to access values through connected objects when it's possible that a reference or function may be undefined or null, hence, protecting you from getting null exception on null/undefined objects.

var ThisArray = [];
ThisArray["a"] = [];
ThisArray["a"]["b"] = [];
ThisArray["a"]["b"]["c"] = "This is a string.";

console.log(ThisArray.a.b.c?.d?.e);

answered Apr 7, 2021 at 20:10

Ran Turner

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Comments

Brandon McConnell · Accepted Answer · 2021-04-07 20:13:43Z

0

This is a perfect place to use optional chaining!

You can do so like this:

if (typeof ThisArray.a?.b?.c !== 'undefined') {
  console.log(`ThisArray["a"]["b"]["c"] is defined!`);
}

Here's a full demo:

var ThisArray = [];
ThisArray["a"] = [];
ThisArray["a"]["b"] = [];
ThisArray["a"]["b"]["c"] = "This is a string.";

if (typeof ThisArray.a?.b?.c !== 'undefined') {
  console.log(`ThisArray["a"]["b"]["c"] is defined!`);
  console.log(`ThisArray.a.w.c === "${ThisArray.a.b.c}"`)
} else {
  console.log(`ThisArray["a"]["b"]["c"] is NOT defined!`);
}

answered Apr 7, 2021 at 20:13

Brandon McConnell

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Comments

Subhojit Khara · Accepted Answer · 2021-04-07 20:20:46Z

0

go with try catch

var thirdDimensionValue = null;
try{
thirdDimensionValue = ThisArray["a"]["b"]["c"]
}
catch{
thirdDimensionValue = null
}
if(thirdDimensionValue){
console.log("value exist")
}
else{
console.log("No value exist in the property")
}

edited Apr 7, 2021 at 20:20

answered Apr 7, 2021 at 20:14

Subhojit Khara

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