Two dimensional array in JS

twoDimensionalArray.js

/*
It is common to address two-dimensional array problems with nested arrays.
It works, but then you have all these nasty references like array[0][3].
This class abstracts the element selection to a method which takes the x and y indices
as arguments.

If you wanted to go purely functional obviously you can, but this class demonstrates the idea.
*/

class TwoDimensionalArray {
  constructor(array, xDim) {
    if (array.length % xDim !== 0) {
      throw new Error(`Your array is not rectangular! Length: ${array.length}, x-dimension: ${xDim}`)
    }
    this.array = array
    this.xDim = xDim
  }

  index(x, y) {
    return this.array[(y * this.xDim) + x]
  }
}

const incrementalArray = size => new Array(size).fill(0).map((_, i) => i)

const xDim = 4
const yDim = 3
const twoDArr = new TwoDimensionalArray(incrementalArray(xDim * yDim), xDim)

// access elements in our array
const xs = incrementalArray(xDim)
const ys = incrementalArray(yDim)
ys.forEach(y => {
  xs.forEach(x => {
    console.log(`x: ${x}, y: ${y}, res: ${twoDArr.index(x, y)}`)
  })
})