Messing around with multidimensional arrays in JS.

default-multidimension-array.js

const createMultidimensionalArray = (dimensions, defaultValue = undefined) => {
    if (dimensions < 1) {
        throw new Error('Dimensions must be greater than 0');
    }
    return new Proxy([], {
        get(target, prop) {
            if (!(prop in target)) {
                if (dimensions === 1) {
                    return defaultValue;
                }
                target[prop] = createMultidimensionalArray(dimensions - 1, defaultValue);
            }
            return target[prop];
        },
        set(target, prop, value) {
            if (dimensions === 1) {
                target[prop] = value;
            }
            // no-op
        },
    });
};

// Regular array
const regArray = createMultidimensionalArray(1);
regArray[1] === undefined;
regArray[1] = 1000;
regArray[1] === 1000;

// 5-dimension array with default value of 0
const fiveArray = createMultidimensionalArray(5, 0);
fiveArray[1][2][3][4][5] === 0;
fiveArray[1][2][3][4][5] = 10;
fiveArray[1][2][3][4][5] === 10;
delete fiveArray[1][2][3][4][5];
fiveArray[1][2][3][4][5] === 0;