cell.js

function Cell(i, j) {
  this.i = i;
  this.j = j;

  this.f = 0;
  this.g = 0;
  this.h = 0;

  this.walls = [true, true, true, true]; // top, right, bottom, left
  this.visited = false;

  this.previous = undefined;

  this.checkNeighbors = function() {
    var neighbors = [];

    var top = grid[index(i, j - 1)];
    var right = grid[index(i + 1, j)];
    var bot = grid[index(i, j + 1)];
    var left = grid[index(i - 1, j)];

    if (top && !top.visited) {
      neighbors.push(top);
    }
    if (right && !right.visited) {
      neighbors.push(right);
    }
    if (bot && !bot.visited) {
      neighbors.push(bot);
    }
    if (left && !left.visited) {
      neighbors.push(left);
    }

    if (neighbors.length > 0) {
      var r = floor(random(0, neighbors.length));
      return neighbors[r];
    } else {
      return undefined;
    }
  }

  this.getNeighbors = function() {
    var neighbors = [];

    var top = grid[index(i, j - 1)];
    var right = grid[index(i + 1, j)];
    var bot = grid[index(i, j + 1)];
    var left = grid[index(i - 1, j)];

    if (top && !top.visited && walls[0]) {
      neighbors.push(top);
    }
    if (right && !right.visited && walls[1]) {
      neighbors.push(right);
    }
    if (bot && !bot.visited && walls[2]) {
      neighbors.push(bot);
    }
    if (left && !left.visited && walls[3]) {
      neighbors.push(left);
    }

    return neighbors;
  }

  this.show = function() {
    var x = this.i * w;
    var y = this.j * w;
    stroke(255);

    if (this.walls[0]) {
      line(x, y, x + w, y);
    }
    if (this.walls[1]) {
      line(x + w, y, x + w, y + w);
    }
    if (this.walls[2]) {
      line(x + w, y + w, x, y + w);
    }
    if (this.walls[3]) {
      line(x, y + w, x, y);
    }
    if (this.visited) {
      noStroke();
      fill(255, 0, 255, 100);
      rect(x, y, w, w);
    }
  }

  this.highlight = function() {
    var x = this.i * w;
    var y = this.j * w;
    noStroke();
    fill(0, 0, 255, 100);
    rect(x, y, w, w);
  }
}