Extend class and call super-method

Question

i try to create an Function to extend a "Class" in JavaScript.

function Extend(clazz, extend, info) {
    var properties  = {};

    if(typeof(info) != 'undefined') {
        properties.info = {
            value: info
        };
    } else {
        properties.info = {
            value: {
                name:       'Unknown',
                author:     'Unknown',
                version:    '0.0.0'
            }
        };
    }

    clazz.prototype = Object.create(extend.prototype, properties);
    eval(clazz.name + ' = clazz;');
}

Here is the Super-Class:

function Module() {
    this.isRegistred = function isRegistred() {
        return true;
    };

    this.start = function start() {
        /* Override Me */
    };

    this.stop = function stop() {
        /* Override Me */
    };

    this.kill = function kill() {
        /* Override Me */
    };

    this.onJoin = function onJoin(user) {
        /* Override Me */
    };

    this.onLeave = function onLeave(user) {
        /* Override Me */
    };

    this.onDice = function onDice(event) {
        /* Override Me */
    };

    this.onMessage = function onMessage(sender, text, receiver) {
        /* Override Me */
    };
};

And here the Extended sample:

/**
    @author     Adrian Preuß <a.preuss@ChannelApp.de>
    @version    1.0.0
*/

Extend(function Welcome() {
    this.onJoin = function onJoin(user) {
        user.sendPrivateMessage('Welcome!');
    };
}, Module, {
    name:       'Welcome',
    author:     'Adrian Preuß',
    version:    '1.0.0'
});

When i try to initiate the class and try to call a super-method (see the following sample), an error appears with "function is unknown":

var test = new Welcome();

test.onJoin(new User()); // It work's

console.log(test.info); // The info from the third args

if(test.isRegistred()) { // functtion is not defined
    // Do something...
}

Answer 1

You are trying to extend by prototype , but you don't use prototype in the first place.

When you assign a function to a class using this , you assign the function to the instance, not to the class itself. If you look at Module.prototype , it'll not contain any of your methods.

The clean way to solve your problem is to declare your functions to the prototype :

function Module() {}

Module.prototype.isRegistred = function isRegistred() {
    return true;
};

// And so on...