https://framagames.org/1597-master/js/grid.js

1function Grid(size) {
2  this.size = size;
3
4  this.cells = [];
5
6  this.build();
7}
8
9// Build a grid of the specified size
10Grid.prototype.build = function () {
11  for (var x = 0; x < this.size; x++) {
12    var row = this.cells[x] = [];
13
14    for (var y = 0; y < this.size; y++) {
15      row.push(null);
16    }
17  }
18};
19
20// Find the first available random position
21Grid.prototype.randomAvailableCell = function () {
22  var cells = this.availableCells();
23
24  if (cells.length) {
25    return cells[Math.floor(Math.random() * cells.length)];
26  }
27};
28
29Grid.prototype.availableCells = function () {
30  var cells = [];
31
32  this.eachCell(function (x, y, tile) {
33    if (!tile) {
34      cells.push({ x: x, y: y });
35    }
36  });
37
38  return cells;
39};
40
41// Call callback for every cell
42Grid.prototype.eachCell = function (callback) {
43  for (var x = 0; x < this.size; x++) {
44    for (var y = 0; y < this.size; y++) {
45      callback(x, y, this.cells[x][y]);
46    }
47  }
48};
49
50// Check if there are any cells available
51Grid.prototype.cellsAvailable = function () {
52  return !!this.availableCells().length;
53};
54
55// Check if the specified cell is taken
56Grid.prototype.cellAvailable = function (cell) {
57  return !this.cellOccupied(cell);
58};
59
60Grid.prototype.cellOccupied = function (cell) {
61  return !!this.cellContent(cell);
62};
63
64Grid.prototype.cellContent = function (cell) {
65  if (this.withinBounds(cell)) {
66    return this.cells[cell.x][cell.y];
67  } else {
68    return null;
69  }
70};
71
72// Inserts a tile at its position
73Grid.prototype.insertTile = function (tile) {
74  this.cells[tile.x][tile.y] = tile;
75};
76
77Grid.prototype.removeTile = function (tile) {
78  this.cells[tile.x][tile.y] = null;
79};
80
81Grid.prototype.withinBounds = function (position) {
82  return position.x >= 0 && position.x < this.size &&
83         position.y >= 0 && position.y < this.size;
84};