JAVASCRIPT

javascript fill 2d array

const r = 4;
const c= 3;
const a = new Array(r).fill(new Array(c).fill(-1));

javascript fill 2 dimensional array

const fillSquareMatrix = (size) => {
  return Array(size)
    .fill()
    .map((u,y) => Array(size)
         .fill()
         .map((u,x) => y * size + x + 1));
};

console.log(fillSquareMatrix(3));