Minesweeper cover

let size = 40
let edge = 3
let cells = []

class Cell {
  constructor(x, y) {
    this.x = x
    this.y = y
    this.hidden = true
  }
  draw() {
    if (this.hidden) {
      fill(200, 200, 200)
      triangle(this.x, this.y,
               this.x + size, this.y,
               this.x, this.y + size)
      fill(150, 150, 150)
      triangle(this.x + size, this.y + size,
               this.x + size, this.y,
               this.x, this.y + size)
      fill(175, 175, 175)
      square(this.x + edge, this.y + edge,
             size - 2 * edge)
    } else {
      noFill()
      stroke(175)
      strokeWeight(0.5)
      square(this.x, this.y,
            size)
      noStroke()
    }
  }
  show() {
    this.hidden = false
  }
}

class Mine extends Cell {
  constructor(x, y) {
    super(x, y)
    this.observers = []
  }
  addObserver(obs) {
    this.observers.push(obs)
  }
  show() {
    super.show()
    for (let obs of this.observers) {
      if (obs.hidden)
        obs.show()
    }
  }
}

class Model {
  constructor(w, h, n=10) {
    this.cells = []
    this.mines = []
    for (let i = 0; i < w; i+=size) {
      this.cells.push([])
      for (let j = 0; j < h; j+=size)
        this.cells[i / size].push(new Cell(i, j))
    }
    let i = 0
    while (i < n) {
      let x = Math.floor(random() * w / size)
      let y = Math.floor(random() * h / size)
      let bx = x * size
      let by = y * size
      if (!(this.cells[x][y] instanceof Mine)) {
        this.cells[x][y] = new Mine(bx, by)
        for (let mine of this.mines) {
          mine.addObserver(this.cells[x][y])
          this.cells[x][y].addObserver(mine)
        }
        this.mines.push(this.cells[x][y])
        i++
      }
    }
  }
}

let modelo

function mousePressed() {
  let x = Math.floor(mouseX / size)
  let y = Math.floor(mouseY / size)
  if (x < modelo.cells.length && y < modelo.cells[0].length)
    modelo.cells[x][y].show()
}

function setup() {
  createCanvas(400, 400);
  noStroke()
  modelo = new Model(width, height)
}

function draw() {
  background(205)
  for (let row of modelo.cells) {
    for (let cell of row)
      cell.draw()
  }
}