1. const sudokuGrid = [
2.   [5, 3, 0, 0, 7, 0, 0, 0, 0],
3.   [6, 0, 0, 1, 9, 5, 0, 0, 0],
4.   [0, 9, 8, 0, 0, 0, 0, 6, 0],
5.   [8, 0, 0, 0, 6, 0, 0, 0, 3],
6.   [4, 0, 0, 8, 0, 3, 0, 0, 1],
7.   [7, 0, 0, 0, 2, 0, 0, 0, 6],
8.   [0, 6, 0, 0, 0, 0, 2, 8, 0],
9.   [0, 0, 0, 4, 1, 9, 0, 0, 5],
10.   [0, 0, 0, 0, 8, 0, 0, 7, 9]
11. ];
12.  
13. function solveSudoku(grid) {
14.  //iterate over every cell in grid
15.   for (let row = 0; row < 9; row++) {
16.     for (let col = 0; col < 9; col++) {
17.       if (grid[row][col] === 0) {
18.         for (let num = 1; num <= 9; num++) {
19.  //check if num can be placed in current cell
20.           if (isValid(grid, row, col, num)) {
21.             grid[row][col] = num;
22.  
23.             if (solveSudoku(grid)) {
24.               return grid;
25.             }
26.  
27.             grid[row][col] = 0;
28.           }
29.         }
30.         return false;
31.       }
32.     }
33.   }
34.  //if prgram doesnt break before reaching here, all cells are filled
35.   return true;
36. }
37.  
38. console.log(solveSudoku(sudokuGrid));