Implementing two-dimensional arrays with Maps in Javascript

Question

I am using a two-dimensional array in some code which I would like to replace with a more suitable data structure in context, namely a Map. I would like to use the Map methods, also hope that the performance will improve that way. However, I run into the following problem:

const myMap = new Map();
myMap.set([1,2],"some value");
console.log(myMap.get([1,2]));

This returns undefined. I kind of understand why this is the case, but it is inconvenient. The following works, but it cannot be used in practice. (Imagine that I want to check the map at some coordinate which results from some computation, it just cannot refer to the same coordinate where the Map was set.)

const myMap = new Map();
const someCoord = [1,2];
myMap.set(someCoord,"some value");
console.log(myMap.get(someCoord));

Are there any workarounds for this? Or are maps not suitable for this kind of implementation of two-dimensional arrays?

You could stringify the array, and then use that as the key. — Nick Parsons
– Nick Parsons, Commented Apr 7, 2020 at 7:52
If you were to stringify the array (JSON.stringify or Array#join) you could also use plain objects instead of maps — nick zoum
– nick zoum, Commented Apr 7, 2020 at 7:55

Code Maniac · Accepted Answer · 2020-04-07 07:54:45Z

1

Two different object can never evaluate as true using comparison, you can use strings as key instead of array

const myMap = new Map();
myMap.set([1, 2].toString(), "some value");
console.log(myMap.get([1, 2].toString()));

answered Apr 7, 2020 at 7:54

Code Maniac

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