javascript練習-私有狀態

javascript練習-私有狀態

在經典的面向物件程式設計中，經常需要將物件的某個狀態封裝或隱藏在物件內，只有通過物件的方法才能訪問這些狀態，對外只暴露一些重要的狀態可以直接編寫。這是就需要私有狀態。

function Range(from, to){
  this.from = function(){return from;}
  this.to = function(){return to;}
}

Range.prototype = {
  constructor: Range,
  includes:function(x){return this.from() <= x && x <= this.to();},
  foreach:function(f){
    for(var x = Math.ceil(this.from()),max = this.to();x < max;x++)f(x);
  },
  toString:function(){
    return "(" + this.from() + "..." + this.to() + ")";
  }
}