JS Class inheritance

Requirements

• class.js

Best practice of defining a Class

See the code example below how to define a Javascript Class with private, public and static members (according this video). This format is used while using the class.js to make classic Class inheritance possible for your Javascript projects.

// self executing function, so this Class has it's own scope
( function() {
    
    // public static member
    MyClass.STATIC_MEMBER = "value";
    
    // private member
    var _privateMember;
    
    // constructor
    function MyClass( value ) {
        _privateMember = value;
        
        // public getter
        this.getPrivateMember = function() {
            return _privateMember;
        };
        
        // public setter
        this.setPrivateMember = function( value ) {
            _privateMember = value;
        };
    };
    
    // expose this Class for public usage
    window.MyClass = Class.extend( MyClass );
    
    // public member
    MyClass.prototype.publicMember = "value";
    
    // public method
    MyClass.prototype.publicMethod = function() {
        privateMethod( this );
    };
    
    // private method
    function privateMethod( context ) {
        console.log( context.publicMethod );
    };
    
})( window );

Note: order of class members and methods

Make sure you define your prototype members and methods after you called Class.extend!

Accessing subclasses

If you have overridden a public method, you can still access the method in it's subclass. This can be done by calling the this.parent method.

Subclass

( function() {
    
    function MySubclass() {};
    
    window.MySubclass = Class.extend( MySubclass );
    
    MySubclass.prototype.say = function( value ) {
        console.log( value );
    };
    
})( window );

Extended class

( function() {
    
    function MyExtendedClass() {};
    
    window.MyExtendedClass = MySubclass.extend( MyExtendedClass );
    
    MyExtendedClass.prototype.say = function( value ) {
        this.parent( "I'm saying " + value );
    };
    
})( window );