How to set up JavaScript namespace and classes properly?

TruMan1 picture TruMan1 · Jul 25, 2012 · Viewed 28.9k times · Source

It seems there are so many ways to set up a JavaScript application so it is confusing as to which one is correct or best. Are there any difference to the below techniques or a better way of doing this?

MyNamespace.MyClass = {
    someProperty: 5,
    anotherProperty: false,

    init: function () {
        //do initialization
    },

    someFunction: function () {
        //do something
    }
};

$(function () {
    MyNamespace.MyClass.init();
});

Another way:

MyNamespace.MyClass = (function () {
    var someProperty = 5;
    var anotherProperty = false;

    var init = function () {
        //do something
    };

    var someFunction = function () {
        //do something
    };

    return {
        someProperty: someProperty
        anotherProperty: anotherProperty
        init: init
        someFunction: someFunction
    };
}());

MyNamespace.MyClass.init();

The first technique feels more like a class. I am coming from server-side background if this makes a difference. The second technique seems more redundant and a bit awkward, but I see this used a lot too. Can someone please help shed some light and advise the best way to move forward? I want to create a application with lots of classes talking to each other.

Answer

Naftali aka Neal picture Naftali aka Neal · Jul 25, 2012

Do neither of those things.

Make a javascript "class":

var MyClass = function () {

    var privateVar; //private
    var privateFn = function(){}; //private 

    this.someProperty = 5;  //public
    this.anotherProperty = false;  //public
    this.someFunction = function () {  //public
        //do something
    };

};

MyNamespace.MyClass = new MyClass();

One with static vars:

var MyClass = (function(){

    var static_var; //static private var

    var MyClass = function () {

        var privateVar; //private
        var privateFn = function(){}; //private 

        this.someProperty = 5;  //public
        this.anotherProperty = false;  //public
        this.someFunction = function () {  //public
            //do something
        };
    };

    return MyClass;

})();

MyNamespace.MyClass = new MyClass();

With a "constructor" (all of the examples have a "constructor", this one just has parameters to work with):

var MyClass = function (a, b c) {

    //DO SOMETHING WITH a, b, c <--

    var privateVar; //private
    var privateFn = function(){}; //private 

    this.someProperty = 5;  //public
    this.anotherProperty = false;  //public
    this.someFunction = function () {  //public
        //do something
    };

};

MyNamespace.MyClass = new MyClass(1, 3, 4);

With all of the above you can do:

MyNamespace.MyClass.someFunction();

But you cannot do (from the outside):

MyNamespace.MyClass.privateFn(); //ERROR!