Javascript inheritance

I have a simple class inheritance in JS:

var Class = function(){};

Class.extend = function(){

    var Extended = function(constructor){

        function extend_obj(destination, source) {
            for(var property in source){
                if(typeof source[property] === "object" && source[property] !== null && destination[property]){ 
                    extend_obj(destination[property], source[property]);
                }else{
                    destination[property] = source[property];
                }
            }
        };

        extend_obj(Extended.prototype, constructor);

        this.constructor.init();
    };

    Extended.init = function(){};

    for(var key in this.prototype){
        Extended.prototype[key] = this.prototype[key];
    }

    Extended.prototype.constructor = Extended;

    for (var key in this) {
        Extended[key] = this[key];
    };

    return Extended;
};

Which allow me to do so:

var SubClass = Class.extend();

SubClass.static_property = "a static property";

SubClass.static_method = function(){
    return "a static method";
};


SubClass.prototype.a_new_property = "something new"; //instance method

var instance = new SubClass({
    name: "custom name"
});

SubClass.init = function(){
    //custom constructor
};

this.constructor.static_method_or_property //call instance method

I need:

• multiple inheritance
• the possibility to use module pattern

There's a cleaner/better/faster way to do that?