Javascript Constructor to Initialize Private Variables

Question

Ok, so I'm using the following skeleton code to create a Javascript Library

var Device = (function(window, document, $) {
    function func_1(){
         return 1;
    }

    function func_2(){
        return 2;
    }

    var internalDevice = {
        func_1: func_1,
        func_2: func_2
    };
    return internalDevice; // expose functionality to the rest of the code
})(window, document, jQuery);

Essentially, I would call my functions like so: Device.func_1(); .

I'm looking to add a constructor that will initialize some private variables from the get-go ie as soon as the object is created, and without having to make any extra function call(s).

How do I do this?!

Thanks.

Answer 1

May be try this way? private_1 and private_2 can only be accessible through function calls while you can use Device() constructor.

function Device(param1, param2) {
    var private_1= param1;
    var private_2= param2;

    this.func_1= function() {
        return private_1;                
    }

    this.func_2= function() {
        return private_2;            
    }
}

var myDevice = new Device(1, 2);
alert(myob.func_1()); 

or may be like this:

var Device = (function(window, document) {
    var private_1;

    function init(param1) {
      private_1 = param1;
    }

    function func_1(){
         return private_1;
    }

    function func_2(){
        return 2;
    }

    var internalDevice = {
        func_1: func_1,
        func_2: func_2,
        init  : init
    };
    return internalDevice; // expose functionality to the rest of the code
})(window, document);

Device.init(10);
alert(Device.func_1())

Answer 2

I managed to figure this one out, here's how I did it:

var Device = (function(window, document, $) {
    var var_1 = 10,
    var_2 = 20,
    var_3;

    function init(){
         var_3 = 30;
    }

    function func_1(){
         return 1;
    }

    function func_2(){
         return 2;
    }

    var internalDevice = {
        init: init(),
        func_1: func_1,
        func_2: func_2
    };
    return internalDevice;
})(window, document, jQuery);

So when you call Device.func_2(); , the variables would already have been initialized. You can see a live example here: http://jsfiddle.net/CZjYH/11/

I am also going to be implementing Amplify.JS functionality inside the init function as a way of persisting my variables to local or Session storage.

Cheers.

Answer 3

var Device = (function(window, document, $, undefined)
{
    return $.extend(function()
    {
        // constructor
    },
    {
        prototype:
        {
            func_1: function func_1()
            {
                return 1;
            },
            func_2: function func_1()
            {
                return 2;
            }
        }
    });
})
(window, window.document, jQuery);

OR

var Device = (function(window, document, $, undefined)
{
    var DevicePrivate = function()
    {
        // constructor
    };

    DevicePrivate.prototype =
    {
        func_1: function()
        {
            return 1;
        },
        func_2: function()
        {
            return 2;
        }
    };

    return DevicePrivate;
})
(window, window.document, jQuery);