javascript - jQuery 扩展复制之前的闭包

Question

描述

在我的示例中，我尝试定义一个带有 private 成员和 public getter 的简单类(称为 Car)。我还有另一个对象，我想将其映射到我的类的实例中。我正在使用 jQuery.extend() 来实现此目的，并且它运行良好，除非该成员是私有(private)的(与此无关)。我猜测这是因为 getter 函数已经关闭了对象创建时定义的值。

我仍然希望能够在 .extend() 之后重新关闭该成员的函数，以便它将反射(reflect)新值，任何人都可以帮助我实现这一目标吗？

我还尝试扩展传入的对 {} 对象的引用，然后使用该空白对象作为目标，如下所示:

function mapToObject(template, json) {
    var b = $.extend(true,{}, template);
  return $.extend(true, b, json);
}

这也没有打破之前的封闭。

我的代码:

// simple class with private member
function Car() {
  var noOfWheels = 2;
  this.honk = function() {
    alert(noOfWheels);
  }
}
// method which converts JSON object to a more typed class object
function mapToObject(template, json) {
  return $.extend(true, template, json);
}

// sample Object , in reality coming from AJAX response
var t = {
  noOfWheels: 5
};
// i want to map t to an instance of Car
var r = mapToObject(new Car, t);// closing here during new Car, i think
r.honk(); // this alerts 2 not 5 because of closure!

fiddle :

https://jsfiddle.net/sajjansarkar/samj3pjq/2/

[编辑]我的解决方案基于 DrFlink 的答案:

// one class
function Car(options) {
  var settings = $.extend({
    noOfWheels: 2
  }, options || {});
  this.honk = function() {
    alert(settings.noOfWheels);
  }
}
// another class
function Lemon(options) {
  var settings = $.extend({
    color: null
  }, options || {});
  this.getColor = function() {
    alert(settings.color);
  }
}
// function to map any json to a template class instance
function ObjectMapperFactory(template, json) {
  if (!jQuery.isArray(json)) {
    return new template(json);
  } else {
    var returnArray = [];
    $(json).each(function() {
      returnArray.push(new template(this))
    });
    return returnArray;
  }
}

//test 1
var carJSON = {
  noOfWheels: 5
};
var c = ObjectMapperFactory(Car, carJSON);
c.honk();
//test2 -different class and also testing array
var lemonJSON = [{
  color: "yeller"
},{
  color: "red"
}];

var c = ObjectMapperFactory(Lemon, lemonJSON);
c[0].getColor();
c[1].getColor();

更新的 fiddle :

https://jsfiddle.net/sajjansarkar/samj3pjq/3/

Answer 1

你为什么要这样做？也许这会更简单:

// simple class with private member
var Car = function(options) {
  var settings = $.extend({
    noOfWheels: 2
  }, options || {});

  // Public method - can be called from client code
  this.honk = function(){
    alert(settings.noOfWheels);
  };

  // Private method - can only be called from within this object
  var myPrivateMethod = function(){
    alert('This is private!');
  };
};

// sample Object
var t = {
  noOfWheels: 4
};

var I = new Car(t);
var J = new Car({
  noOfWheels: 6
});

I.honk();
J.honk();