.js

 function Cell(val) {
    this.empty = false;
    this.value = val;
  }
  Cell.prototype.reset = function () {
    this.empty = true;
    this.value = null;
  };
  
  var grid = []
  for (var x=0; x<10; x++) {
    grid[x] = []
    for (var y=0; y<10; y++) {
      grid[x][y] = new Cell(1);
    }
  }
  
  floodFill = function(grid, x, y) {
    if (x < 0 || x >= 10) return
    if (y < 0 || y >= 10) return
    if (!grid[x][y].empty) return
    grid[x][y].reset()
  
    floodFill(grid, x, y + 1)
    floodFill(grid, x + 1, y)
    floodFill(grid, x, y - 1)
    floodFill(grid, x - 1, y)
  }