Inheritance at javascript

Kelas.js

Kelas = function() {
    var c = function() {
        if (this.initialize) {
            this.initialize.apply(this, arguments);
        }
    }
 
    function Extend(dst, src) {
        for (var i in src) {
            try {
                dst[i] = src[i];
            } catch (e) {
            }
        }
        return dst;
    }
 
    c.prototype = Object.create(Kelas.prototype);
    for (var i = 0; i < arguments.length; i++) {
        var a = arguments[i];
        if (a.prototype) {
            c.prototype = new a();
        } else {
            Extend(c.prototype, a);
        }
    }
    c.prototype.constructor = c;
    Extend(c, c.prototype);
    return c;
}