How do I make 2D array data members in Javascript?

Question

What I have now are data members, each with a varying number of arrays with a length of 4:

const obj={
    member1:{
        a1:[1,2,3,-4],
        a2:[0,1,-8,-1],
        a3:[-.10,9,5,110]
    }
    member2:{
        a1:[1,0,8,-4],
        a2:[-11,1,-8,-67],
        a3:[-.10,2,5,110]
        a4:[108,15,16, 17]
    }
    //...and so on
}

But I would prefer each data member to have a 2D array of various sizes, something like:

const obj={
   member1:{
      //2D array of a unique size
   }
   member2:{
      //2D array of another unique size
   }
   //...and so on
}

Answer 1

If you are looking to make a 2D array, you can simply build them like this :

const obj={
    member1:{
        a : [
            [1,2,3,-4],
            [0,1,-8,-1],
            [-.10,9,5,110]
        ]
    }
    member2:{
        a : [
            [1,0,8,-4],
            [-11,1,-8,-67],
            [-.10,2,5,110]
            [108,15,16, 17]
        ]
    }
    //...and so on
}

And access them as you usually do :

obj.member1.a[0][1] // for instance