How to determine if an array includes another array in JS?

Question

I'm wondering what the best way to determine the membership of one array in another array in JS.

Here's an example

let a = [];
a.push([1,2]);
a.includes([1,2]) <- evaluates to false
a.indexOf([1,2]) <- evaluates to -1

What's the deal here? Any efficient work around?

Very simple.... they are not the same array object reference. `[1,2] !== [1,2]` — charlietfl, Sep 21 '19 at 13:32
Then how can I find out if there is an object with the same two numbers? — Tim Carew, Sep 21 '19 at 13:34
Please refer to this question: https://stackoverflow.com/questions/38811421/check-if-an-array-is-subset-of-another-array — Dhruv Patel, Sep 21 '19 at 13:42

score 0 · Answer 1 · answered Sep 21 '19 at 13:45

At the moment, your search array doesn't actually equal the array within your a array as they have 2 different references in memory. However, you could convert your arrays to strings, such that your search can equal another string array within your array.

To do this you could convert your inner arrays to string using .map(JSON.stringify) and then search for the string version of your array using .includes(JSON.stringify(search_arrr)).

See example below:

let a = [];
let search = [1, 2];
a.push([1,2]);

a = a.map(JSON.stringify)
console.log(a.includes(JSON.stringify(search)));

How to determine if an array includes another array in JS?

1 Answers1