Javascript two dimensional array

// declaration of a two-dimensional array
// 5 is the number of rows and 4 is the number of columns.
const matrix = new Array(5).fill(0).map(() => new Array(4).fill(0));

console.log(matrix[0][0]); // 0

var array = [
  ["0, 0", "1, 0", "2, 0", "3, 0", "4, 0"],
  ["0, 1", "1, 1", "2, 1", "3, 1", "4, 1"],
  ["0, 2", "1, 2", "2, 2", "3, 2", "4, 2"],
  ["0, 3", "1, 3", "2, 3", "3, 3", "4, 3"],
  ["0, 4", "1, 4", "2, 4", "3, 4", "4, 4"],
  ]; // Think of it as coordinates, array[x, y] x = 0; y = 0; is "0, 0" on 
	// this grid

console.log(array[3][3]); // returns "3, 3"
// If you use graphics (ex: p5js or JS Canvas) then this will be a 5x5 map.
// Useful for roguelikes and/or raycasters.

//2D array
let activities = [
    ['Work', 9],
    ['Eat', 1],
    ['Commute', 2],
    ['Play Game', 1],
    ['Sleep', 7]
];

var grid = [];
iMax = 3;
jMax = 2;
count = 0;

    for (let i = 0; i < iMax; i++) {
      grid[i] = [];

      for (let j = 0; j < jMax; j++) {
        grid[i][j] = count;
        count++;
      }
    }

// grid = [
//   [ 0, 1 ]
//   [ 2, 3 ]
//   [ 4, 5 ]
// ];

console.log(grid[0][2]); // 4

//example of two dimensional array
var grid = [
  ["a", "b"],
  ["c", "d"],
  ["e", "f"]
];
console.log(grid[0][0]); // a
console.log(grid[1][1]); // d
console.log(grid);