Question

您如何处理在其子女之间共享原型参考属性的问题？有没有任何众所周知的模式（除了在构造函数中重新定义属性之外）来解决这个问题？这是一个问题，还是我遗漏了一些关于原型继承的东西？

示例：

var dog = 
{
    name: "no-name",
    paws: ["front-right", "front-left", "back-right", "back-left"]
};

var rex = Object.create(dog);
rex.name = "Rex";

var bingo = Object.create(dog);
bingo.name = "Bingo";
bingo.paws.pop(); //Bingo is just like a dog, but has lost a paw in a tragic accident

console.log(bingo.paws); //["front-right", "front-left", "back-right"]
console.log(rex.paws); //Rex lost a paw too! ["front-right", "front-left", "back-right"]

UPDATE：

在研究了原型继承之后，在我看来，在这个范例中编程的“自然”方式是扩展对象，而不是过于依赖于构造函数，而是将它们用作“类”。我在博客上看到的例子（它似乎也与Douglas Crockford的Object.create一致）或多或少是这样的：

var Dog = 
{
    name: "no-name",
    paws: ["front-right", "front-left", "back-right", "back-left"],
    bark: function() { alert("Bark!!"); }
};

//No constructor acting like a "class"
var BigDog = Object.create(Dog);
BigDog.bark = function() { alert("WOLF!!!"); };

var thor = Object.create(BigDog);
thor.name = "Thor";
thor.bark();

构造函数是在新实例上复制或创建新数组的唯一方法吗？这种模式Object.create“不完整”吗？

感谢您的回答！

Answer 1

如您所知，对象的原型是一个包含构成该对象的基本属性的对象。与所有对象一样，该原型对象是名称到值的映射。 javascript中的数组（和对象）总是通过引用传递，因此当在原型上调用Object.create时 - 它只是将数组的引用复制到新对象中。正如TheZ在评论中所说，你可以这样做：

function Dog(){
    this.paws = ['front-right', 'front-left', 'back-right', 'back-left'];
}
Dog.prototype = {
    name: 'no-name',
    paws: null
};

现在我们可以创建我们的对象了：

var rex = new Dog();
rex.name = 'Rex';

var bingo = new Dog();
bingo.name = 'Bingo';
bingo.paws.pop();

Answer 2

您应该查看模块模式

制作一个可以使用的封口，这样你的狗就可以分开了

var dog = function(){
 //private
 var name = "no-name";
 var paws = ["front-right", "front-left", "back-right", "back-left"];

 //public
 function getName(){
  return name;
 }

 function setName(newName){
  name = newName;
 }

 function getPaws(){
  return paws;
 }

 function pawPain(){
  paws.pop();
 }

 //expose
 return{
  pawPain: pawPain,
  getPaws: getPaws,
  getName: getName,
  setName: setName
 };
};

现在你可以用它来制作新狗了

var rex = new dog();    
var bingo = new dog();
rex.pawPain();
console.log(bingo.getPaws());

Answer 3

http://jsfiddle.net/sVaSp/

只需要一个构造函数。每个版本都拥有自己的对象副本。

    function dog(name) {
        this.name = "no-name",
        this.paws = ["front-right", "front-left", "back-right", "back-left"]
    } 

    var rex = new dog();
    rex.name = "Rex";

    var bingo = new dog();
    bingo.name = "Bingo";
    bingo.paws.pop(); //Bingo is just like a dog, but has lost a paw in a tragic accident

    console.log(bingo.paws); //["front-right", "front-left", "back-right"]
    console.log(rex.paws); //Rex lost a paw too! ["front-right", "front-left", "back-right"]

Object.create和引用属性

UPDATE：

3 个答案: