使用「這個」對象在JavaScript

Question

我想聲明一個JavaScript對象，像這樣：

var Calculator = function() { 
    this.textbox = new Textbox({ 
     ... 
    }); 
    this.btn1 = new Button ({ 
     ... 
     onClick: function() { 
      this.textbox.value += "1"; 
    }); 
    ... 
}; 

我做了一些調試，發現裏面this.btn1的this對象不再指Calculator對象。如何將textbox轉換爲Calculator的textbox？

非常感謝提前！

Answer 1

的var self = this

var Calculator = function() { 
    var self = this; // self is a reference to calculator, always. 

    this.textbox = new Textbox({ 
     ... 
    }); 
    this.btn1 = new Button ({ 
     ... 
     onClick: function() { 
      self.textbox.value += "1"; 
    }); 
    ... 
};