下面是一个模板，我有时会在JavaScript中使用类似oop的行为。如您所见，您可以使用闭包模拟私有(静态和实例)成员。新的MyClass()将返回一个对象，该对象仅具有分配给这个对象和“类”的原型对象中的属性。

var MyClass = (function () {
    // private static
    var nextId = 1;

    // constructor
    var cls = function () {
        // private
        var id = nextId++;
        var name = 'Unknown';

        // public (this instance only)
        this.get_id = function () { return id; };

        this.get_name = function () { return name; };
        this.set_name = function (value) {
            if (typeof value != 'string')
                throw 'Name must be a string';
            if (value.length < 2 || value.length > 20)
                throw 'Name must be 2-20 characters long.';
            name = value;
        };
    };

    // public static
    cls.get_nextId = function () {
        return nextId;
    };

    // public (shared across instances)
    cls.prototype = {
        announce: function () {
            alert('Hi there! My id is ' + this.get_id() + ' and my name is "' + this.get_name() + '"!\r\n' +
                  'The next fellow\'s id will be ' + MyClass.get_nextId() + '!');
        }
    };

    return cls;
})();

有人问过我使用这种模式的继承问题，所以如下:

// It's a good idea to have a utility class to wire up inheritance.
function inherit(cls, superCls) {
    // We use an intermediary empty constructor to create an
    // inheritance chain, because using the super class' constructor
    // might have side effects.
    var construct = function () {};
    construct.prototype = superCls.prototype;
    cls.prototype = new construct;
    cls.prototype.constructor = cls;
    cls.super = superCls;
}

var MyChildClass = (function () {
    // constructor
    var cls = function (surName) {
        // Call super constructor on this instance (any arguments
        // to the constructor would go after "this" in call(…)).
        this.constructor.super.call(this);

        // Shadowing instance properties is a little bit less
        // intuitive, but can be done:
        var getName = this.get_name;

        // public (this instance only)
        this.get_name = function () {
            return getName.call(this) + ' ' + surName;
        };
    };
    inherit(cls, MyClass); // <-- important!

    return cls;
})();

还有一个例子:

var bob = new MyClass();
bob.set_name('Bob');
bob.announce(); // id is 1, name shows as "Bob"

var john = new MyChildClass('Doe');
john.set_name('John');
john.announce(); // id is 2, name shows as "John Doe"

alert(john instanceof MyClass); // true

正如您所看到的，类之间正确地交互(它们共享来自MyClass的静态id, announce方法使用正确的get_name方法，等等)。

需要注意的一点是需要对实例属性进行阴影处理。您实际上可以让继承函数遍历所有实例属性(使用hasOwnProperty)是函数，并自动魔术般地添加一个super_<方法名>属性。这将允许您调用This .super_get_name()，而不是将其存储在临时值中并使用call调用它。

对于原型上的方法，你不需要担心上面的问题，如果你想访问超类的原型方法，你可以调用this.constructor.super.prototype.methodName。如果你想让它不那么冗长，你当然可以添加便利属性。：）

使用原型:

function Box(color) // Constructor
{
    this.color = color;
}

Box.prototype.getColor = function()
{
    return this.color;
};

隐藏“color”(有点像私有成员变量):

function Box(col)
{
   var color = col;

   this.getColor = function()
   {
       return color;
   };
}

用法:

var blueBox = new Box("blue");
alert(blueBox.getColor()); // will alert blue

var greenBox = new Box("green");
alert(greenBox.getColor()); // will alert green

构造函数的意义是什么呢 财产吗?不知道它在哪里 可能有用，有什么想法吗?

构造函数属性的目的是提供某种方式来假装JavaScript有类。你不能做的一件事是在创建对象后更改对象的构造函数。它是复杂的。

几年前我写了一篇相当全面的文章:http://joost.zeekat.nl/constructors-considered-mildly-confusing.html

使用上面Nick的示例，您可以使用return语句作为对象定义中的最后一条语句为不带参数的对象创建构造函数。返回你的构造函数，如下所示，它将在你每次创建对象时运行__construct中的代码:

function Box()
{
   var __construct = function() {
       alert("Object Created.");
       this.color = 'green';
   }

  this.color = '';

   this.getColor = function() {
       return this.color;
   }

   __construct();
}

var b = new Box();

这是一个构造函数:

function MyClass() {}

当你这样做时

var myObj = new MyClass();

MyClass被执行，并返回该类的一个新对象。

我想我会发布我用javascript闭包做的事情，因为还没有人使用闭包。

var user = function(id) {
  // private properties & methods goes here.
  var someValue;
  function doSomething(data) {
    someValue = data;
  };

  // constructor goes here.
  if (!id) return null;

  // public properties & methods goes here.
  return {
    id: id,
    method: function(params) {
      doSomething(params);
    }
  };
};

欢迎对此解决方案提出意见和建议。：）

在我看来，你们大多数人都给出了getter和setter的例子，而不是一个构造函数，即http://en.wikipedia.org/wiki/Constructor_(object-oriented_programming)。

lunch -dan更接近，但是这个例子在jsFiddle中不起作用。

这个例子创建了一个私有构造函数，该函数只在创建对象期间运行。

var color = 'black';

function Box()
{
   // private property
   var color = '';

   // private constructor 
   var __construct = function() {
       alert("Object Created.");
       color = 'green';
   }()

   // getter
   this.getColor = function() {
       return color;
   }

   // setter
   this.setColor = function(data) {
       color = data;
   }

}

var b = new Box();

alert(b.getColor()); // should be green

b.setColor('orange');

alert(b.getColor()); // should be orange

alert(color); // should be black

如果你想要分配公共属性，那么构造函数可以这样定义:

var color = 'black';

function Box()
{
   // public property
   this.color = '';

   // private constructor 
   var __construct = function(that) {
       alert("Object Created.");
       that.color = 'green';
   }(this)

   // getter
   this.getColor = function() {
       return this.color;
   }

   // setter
   this.setColor = function(color) {
       this.color = color;
   }

}

var b = new Box();

alert(b.getColor()); // should be green

b.setColor('orange'); 

alert(b.getColor()); // should be orange

alert(color); // should be black

这种模式对我很有帮助。使用这种模式，你在单独的文件中创建类，“根据需要”将它们加载到整个应用程序中。

// Namespace
// (Creating new if not instantiated yet, otherwise, use existing and just add to it)
var myApp = myApp || {};

// "Package" 
// Similar to how you would establish a package in other languages
(function() {

// "Class"
var MyClass = function(params) {
    this.initialize(params);
}

    // "Private Static" vars 
    //    - Only accessible to functions in this class.
    //    - Doesn't get wiped out when we create a new instance.
    var countInstances = 0;
    var allInstances = [];

    // "Private Static" functions 
    //    - Same as above, but it's a function accessible 
    //      only to other functions in this class.
    function doSomething(){
    }

    // "Public Static" vars
    //    - Everyone has access.
    //    - Doesn't get wiped out when we create a new instance.
    MyClass.counter = 0;

    // "Public Static" functions
    //    - Same as above, but anyone can call this "static method".
    //    - Kinda like a singleton class situation.
    MyClass.foobar = function(){
    }

    // Public properties and methods are built into the "prototype"
    //    - This is how each instance can become unique unto itself.
    //    - Establishing "p" as "local" (Static Private) variable 
    //      simply so we don't have to keep typing "MyClass.prototype" 
    //      for each property and function.
var p = MyClass.prototype;

    // "Public" vars
    p.id = null;
    p.firstname = null;
    p.lastname = null;

    // "Private" vars
    //    - Only used by "this" instance.
    //    - There isn't "true" privacy for each 
    //      instance so we have to fake it. 
    //    - By tradition, we indicate "privacy"  
    //      by prefixing it with an underscore. 
    //    - So technically, anyone can access, but we simply 
    //      don't tell anyone about it (e.g. in your API)
    //      so no one knows about it :)
    p._foo = null;

    p.initialize = function(params){
        this.id = MyClass.counter++;
        this.firstname = params.firstname;
        this.lastname = params.lastname;
        MyClass.counter++;
        countInstances++;
        allInstances.push(this);
    }

    p.doAlert = function(theMessage){
        alert(this.firstname + " " + this.lastname + " said: " + theMessage + ". My id:" + this.id + ".  Total People:" + countInstances + ". First Person:" + allInstances[0].firstname + " " + allInstances[0].lastname);
    }


// Assign class to app
myApp.MyClass = MyClass;

// Close the "Package"
}());

// Usage example:
var bob = new myApp.MyClass({   firstname   :   "bob",
                                lastname    :   "er"
                            });

bob.doAlert("hello there");

我发现这个教程非常有用。大多数jQuery插件都使用这种方法。

http://www.htmlgoodies.com/html5/tutorials/create-an-object-oriented-javascript-class-constructor.html#fbid=OVYAQL_TDpK

var Class = function(methods) {   
    var klass = function() {    
        this.initialize.apply(this, arguments);          
    };  

    for (var property in methods) { 
       klass.prototype[property] = methods[property];
    }

    if (!klass.prototype.initialize) klass.prototype.initialize = function(){};      

    return klass;    
};

现在,

var Person = Class({ 
    initialize: function(name, age) {
        this.name = name;
        this.age  = age;
    },
    toString: function() {
        return "My name is "+this.name+" and I am "+this.age+" years old.";
    }
}); 

var alice = new Person('Alice', 26);
alert(alice.name); //displays "Alice"
alert(alice.age); //displays "26"
alert(alice.toString()); //displays "My name is Alice and I am 26 years old" in most browsers.
//IE 8 and below display the Object's toString() instead! "[Object object]"

例如:http://jsfiddle.net/FZ5nC/

试试这个模板:

<script>
//============================================================
// Register Namespace
//------------------------------------------------------------
var Name = Name||{};
Name.Space = Name.Space||{};

//============================================================
// Constructor - MUST BE AT TOP OF FILE
//------------------------------------------------------------
Name.Space.ClassName = function Name_Space_ClassName(){}

//============================================================
// Member Functions & Variables
//------------------------------------------------------------
Name.Space.ClassName.prototype = {
  v1: null
 ,v2: null
 ,f1: function Name_Space_ClassName_f1(){}
}

//============================================================
// Static Variables
//------------------------------------------------------------
Name.Space.ClassName.staticVar = 0;

//============================================================
// Static Functions
//------------------------------------------------------------
Name.Space.ClassName.staticFunc = function Name_Space_ClassName_staticFunc(){
}
</script>

如果你定义一个静态类，你必须调整你的命名空间:

<script>
//============================================================
// Register Namespace
//------------------------------------------------------------
var Shape = Shape||{};
Shape.Rectangle = Shape.Rectangle||{};
// In previous example, Rectangle was defined in the constructor.
</script>

示例类:

<script>
//============================================================
// Register Namespace
//------------------------------------------------------------
var Shape = Shape||{};

//============================================================
// Constructor - MUST BE AT TOP OF FILE
//------------------------------------------------------------
Shape.Rectangle = function Shape_Rectangle(width, height, color){
    this.Width = width;
    this.Height = height;
    this.Color = color;
}

//============================================================
// Member Functions & Variables
//------------------------------------------------------------
Shape.Rectangle.prototype = {
  Width: null
 ,Height: null
 ,Color: null
 ,Draw: function Shape_Rectangle_Draw(canvasId, x, y){
    var canvas = document.getElementById(canvasId);
    var context = canvas.getContext("2d");
    context.fillStyle = this.Color;
    context.fillRect(x, y, this.Width, this.Height);
 }
}

//============================================================
// Static Variables
//------------------------------------------------------------
Shape.Rectangle.Sides = 4;

//============================================================
// Static Functions
//------------------------------------------------------------
Shape.Rectangle.CreateSmallBlue = function Shape_Rectangle_CreateSmallBlue(){
    return new Shape.Rectangle(5,8,'#0000ff');
}
Shape.Rectangle.CreateBigRed = function Shape_Rectangle_CreateBigRed(){
    return new Shape.Rectangle(50,25,'#ff0000');
}
</script>

示例实例化:

<canvas id="painting" width="500" height="500"></canvas>
<script>
alert("A rectangle has "+Shape.Rectangle.Sides+" sides.");

var r1 = new Shape.Rectangle(16, 12, "#aa22cc");
r1.Draw("painting",0, 20);

var r2 = Shape.Rectangle.CreateSmallBlue();
r2.Draw("painting", 0, 0);

Shape.Rectangle.CreateBigRed().Draw("painting", 10, 0);
</script>

注意函数定义为A.B = function A_B()。这是为了使您的脚本更容易调试。打开Chrome的Inspect Element面板，运行这个脚本，并展开调试回溯:

<script>
//============================================================
// Register Namespace
//------------------------------------------------------------
var Fail = Fail||{};

//============================================================
// Static Functions
//------------------------------------------------------------
Fail.Test = function Fail_Test(){
    A.Func.That.Does.Not.Exist();
}

Fail.Test();
</script>

在使用上面Blixt的伟大模板时，我发现它不能很好地使用多级继承(MyGrandChildClass扩展MyChildClass扩展MyClass)——它循环调用第一个父类的构造函数。这里有一个简单的解决方法-如果你需要多级继承，而不是使用this.constructor.super。调用(这,姓氏);使用chainSuper()。调用(这,姓氏);链函数定义如下:

function chainSuper(cls) {
  if (cls.__depth == undefined) cls.__depth = 1; else cls.__depth++;
  var depth = cls.__depth;
  var sup = cls.constructor.super;
  while (depth > 1) {
    if (sup.super != undefined) sup = sup.super;
    depth--;
  }
  return sup;
}

如果你使用微软开源的Typescript，他们就会这样做:-)

class BankAccount {
 balance: number;
 constructor(initially: number) {
 this.balance = initially;
 }
 deposit(credit: number) {
 this.balance += credit;
 return this.balance;
 }
}

Typescript让你“伪造”OO结构，这些结构被编译成javascript结构。如果你正在开始一个大型项目，它可以为你节省很多时间，而且它刚刚达到里程碑1.0版本。

http://www.typescriptlang.org/Content/TypeScript%20Language%20Specification.pdf

上面的代码被“编译”为:

var BankAccount = (function () {
    function BankAccount(initially) {
        this.balance = initially;
    }
    BankAccount.prototype.deposit = function (credit) {
        this.balance += credit;
        return this.balance;
    };
    return BankAccount;
})();

http://www.jsoops.net/对于Js中的oop非常好。提供私有、受保护、公共变量和函数，并具有继承特性。示例代码:

var ClassA = JsOops(function (pri, pro, pub)
{// pri = private, pro = protected, pub = public

    pri.className = "I am A ";

    this.init = function (var1)// constructor
    {
        pri.className += var1;
    }

    pub.getData = function ()
    {
        return "ClassA(Top=" + pro.getClassName() + ", This=" + pri.getClassName()
        + ", ID=" + pro.getClassId() + ")";
    }

    pri.getClassName = function () { return pri.className; }
    pro.getClassName = function () { return pri.className; }
    pro.getClassId = function () { return 1; }
});

var newA = new ClassA("Class");

//***Access public function
console.log(typeof (newA.getData));
// function
console.log(newA.getData());
// ClassA(Top=I am A Class, This=I am A Class, ID=1)

//***You can not access constructor, private and protected function
console.log(typeof (newA.init));            // undefined
console.log(typeof (newA.className));       // undefined
console.log(typeof (newA.pro));             // undefined
console.log(typeof (newA.getClassName));    // undefined

只是为了提供一些变化。ds。Oop是一种在javascript中使用构造函数声明类的好方法。它支持所有可能的继承类型(包括一种甚至c#都不支持的类型)以及很好的接口。

var Color = ds.make.class({
    type: 'Color',
    constructor: function (r,g,b) { 
        this.r = r;                     /* now r,g, and b are available to   */
        this.g = g;                     /* other methods in the Color class  */
        this.b = b;                     
    }
});
var red = new Color(255,0,0);   // using the new keyword to instantiate the class

在大多数情况下，在调用传递此信息的方法之前，必须以某种方式声明所需的属性。如果你不需要一开始就设置一个属性，你可以像这样在对象中调用一个方法。可能不是最漂亮的方法，但这仍然有效。

var objectA = {
    color: ''; 
    callColor : function(){
        console.log(this.color);
    }
    this.callColor(); 
}
var newObject = new objectA(); 

在JavaScript中调用类型定义了函数的行为:

直接调用 对象上的方法调用obj.func() 构造函数调用new func() 间接调用func.call()或func.apply()

该函数在使用new操作符调用时作为构造函数调用:

function Cat(name) {
   this.name = name;
}
Cat.prototype.getName = function() {
   return this.name;
}

var myCat = new Cat('Sweet'); // Cat function invoked as a constructor

JavaScript中的任何实例或原型对象都有一个属性构造函数，它引用构造函数。

Cat.prototype.constructor === Cat // => true
myCat.constructor         === Cat // => true

查看这篇关于构造函数属性的文章。

是的，你可以像这样在类声明中定义构造函数:

class Rectangle {
  constructor(height, width) {
    this.height = height;
    this.width = width;
  }
}

也许它变得简单了一点，但以下是我在2017年想出的:

class obj {
  constructor(in_shape, in_color){
    this.shape = in_shape;
    this.color = in_color;
  }

  getInfo(){
    return this.shape + ' and ' + this.color;
  }
  setShape(in_shape){
    this.shape = in_shape;
  }
  setColor(in_color){
    this.color = in_color;
  }
}

在使用上面的类，我有以下:

var newobj = new obj('square', 'blue');

//Here, we expect to see 'square and blue'
console.log(newobj.getInfo()); 

newobj.setColor('white');
newobj.setShape('sphere');

//Since we've set new color and shape, we expect the following: 'sphere and white'
console.log(newobj.getInfo());

如您所见，构造函数接受两个参数，我们设置对象的属性。我们还通过使用setter函数改变对象的颜色和形状，并证明在这些改变之后调用getInfo()时它的变化仍然存在。

有点晚了，但我希望这能帮到你。我已经用摩卡单元测试了这个功能，效果很好。

这里我们需要注意一点，它是一种无类语言，但是我们可以通过使用java script中的函数来实现。实现这一点最常见的方法是我们需要在java脚本中创建一个函数，并使用new关键字来创建一个对象，并使用此关键字来定义属性和方法。下面是示例。

// Function constructor

   var calculator=function(num1 ,num2){
   this.name="This is function constructor";
   this.mulFunc=function(){
      return num1*num2
   };

};

var objCal=new calculator(10,10);// This is a constructor in java script
alert(objCal.mulFunc());// method call
alert(objCal.name);// property call

//Constructors With Prototypes

var calculator=function(){
   this.name="Constructors With Prototypes";
};

calculator.prototype.mulFunc=function(num1 ,num2){
 return num1*num2;
};
var objCal=new calculator();// This is a constructor in java script
alert(objCal.mulFunc(10,10));// method call
alert(objCal.name); // property call