原型：“这个”的深度范围访问实例的范围 [英] prototype: deep scope of "this" to access instance's scope

问题描述

如何才能缓存最顶层的范围，以便稍后在原型中更深入地使用，如下所示：

How can the the top-most scope can be cached in order to be used deeper in the prototype later, like so:

var Game = function(id){
   this.id = id;
};

Game.prototype = {
  board : {
    init: function(){
       // obviously "this" isn't the instance itself, but will be "board"
       console.log(this.id);
    }
  }
}

var game = new Game('123');
game.board.init(); // should output "123"

更新：

现在我考虑一下，我可以使用 apply / call 并传递上下文......

update:

Well now that I think about it, I can use apply/call and pass the context...

game.board.init.apply(game);

推荐答案

因为你只有一个<$ c的实例$ c> board 对象，它无法知道您用来访问它的内容。使用 game.board 或 Game.prototype.board 来访问该对象会得到完全相同的结果。

As you only have one instance of the board object, there is no way for it to know what you used to access it. Using game.board or Game.prototype.board to access the object gives exactly the same result.

如果您不想为每个游戏 board 对象>例如，你必须告诉 board 对象它应该认为自己属于每个调用的 Game 对象：

If you don't want to create one board object for each Game instance, you have to tell the board object which Game object it should consider itself to belong to for each call:

game.board.doSomething(game);

或：

Game.prototype.board.doSomething(game);

编辑：

创建一块板对于每个 Game 实例，为 Board 创建一个构造函数，并使board对象知道游戏它所属的实例：

To create one board for each Game instance, make a constructor for Board, and make the board object aware of the Game instance that it belongs to:

function Game(id) {
  this.id = id;
  this.board = new Board(this);
}

Game.prototype = {
};

function Board(game) {
  this.game = game;
}

Board.prototype = {
  init: function(){
    console.log(this.game.id);
  }
};

var game = new Game('123');
game.board.init(); // outputs "123"

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