this

Game.prototype.restart = function () {
  this.clearLocalStorage();
  this.timer = setTimeout(function() {
    this.clearBoard();    // what is "this"?
  }, 0);
};

error: Uncaught TypeError: undefined is not a function

When you invoke setTimeout(), you are actually invoking window.setTimeout(). Therefore, this.clearBoard(); refers to the window object.

Traditional solution

• use var self = this;

Game.prototype.restart = function () {
  this.clearLocalStorage();
  var self = this;   // save reference to 'this', while it's still this!
  this.timer = setTimeout(function(){
    self.clearBoard();    // oh OK, I do know who 'self' is!
  }, 0);
};

New solution

• use the bind() method to pass in the proper reference:

Game.prototype.restart = function () {
  this.clearLocalStorage();
  this.timer = setTimeout(this.reset.bind(this), 0);  // bind to 'this'
};

Game.prototype.reset = function(){
    this.clearBoard();    // ahhh, back in the context of the right 'this'!
};