How to define public and private property in javascript

Question

I want to define public and private property in JavaScript class,

Here you see c# format of my properties.

My question is 'How can I write these properties with JavaScript':

public class MyMath
{
    public static double Pi 
    {
       get {return 3.14;}
    }

    public static int R {get; set;}

    private int MyPrivateProp1 {get; set;}

    public double MyCalcMethod()
    {
           return MyPrivateProp1 * R;
    }
}

I want to use this class like:

var x = MyMath.Pi * MyMath.R;

Thanks in advance for your time.

@Simsons, JavaScript has strong object-oriented programming capabilities. see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Introduction_to_Object-Oriented_JavaScript — Hadi Sharifi, Jan 17 '14 at 09:43
@mini-me You can create private variables within a function that cannot be referenced externally. — Nunners, Jan 17 '14 at 09:57

score 1 · Answer 1 · answered Jan 17 '14 at 09:56

The answer is closures.

var Person = function () {
    var localVariable = "I'm hidden";

    this.publicProperty = "example";

    this.publicFunction = function () {
        // This function has access to the localVariable
        // but nothing outside can get to it directly.
        console.log(localVariable);
        return "aren't I clever?";
    }
};

Person.prototype.staticProperty = "A banana";

Now you can create an instance of your person class:

var aPerson = new Person();
console.log(aPerson.publicProperty);
console.log(aPerson.publicFunction());
console.log(aPerson.staticProperty);
console.log(aPerson.localVaraible) // undefined.

score 1 · Accepted Answer · answered Jan 17 '14 at 10:00

You could create a self-executing function to create your object, this will then allow you to instantly call the variables and methods from your Javascript without having to create an instance of the object.

Example : JSFiddle

var myMath = (function MyMath() {
    this.Pi = 3.14;
    this.R = 0;

    var MyPrivateProp1 = 15;

    this.MyCalcMethod = function() {
      return R * MyPrivateProp1;
    };

    return this;
})();

myMath.R = 5;

var x = myMath.Pi * myMath.R;

console.log(myMath.Pi);
console.log(myMath.R);
console.log(myMath.MyPrivateProp1); //This is returned as Undefined because it is a Private Variable to the Object.
console.log(myMath.MyCalcMethod());
console.log(x);

Notice the return this at the end of the function, this is required to ensure the object is passed to the myMath variable.

score 0 · Answer 3 · answered Jan 17 '14 at 09:49

You could create an object which would store the two variables.

Example:

var MyMath = {}; //Create a new object
MyMath.Pi = 3.14;
MyMath.R = function(value){
    if(value !== undefined){
        this.val=value;
    }// Set
        else return this.val //Get

};

And you could use it like you wanted:

var x = MyMath.Pi * MyMath.R(5);

score 0 · Answer 4 · answered Jan 17 '14 at 10:03

Try this code:

  // define the MyMathClass
    function MyMath() {
        function MyPrivateProp1(){
        //Define get set;
        }
    }
    MyMath.prototype.Pi  = function(){
    //Define get
      return 3.14;
    };

    MyMath.prototype.R = function(){
    //Define get and set
    };


    var MyMath = new MyMath();
    var x = MyMath.Pi() * MyMath.R();

References. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Introduction_to_Object-Oriented_JavaScript https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide http://javascriptissexy.com/oop-in-javascript-what-you-need-to-know/

How to define public and private property in javascript

4 Answers4

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