javascript how to declare 2d matrix code example

Example 1: js initialize 2d array

let data = [];
for (let row=0; row<rows; row++) {
    data.push(new Array(cols).fill('#'));
};

Example 2: javascript two dimensional array

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