Simple mixin function with prototype support

gistfile1.js

function mixin(receiver, source) {
    var descriptors = {};
    for(var name in source) {
        if(source.hasOwnProperty(name)) {
            if(typeof receiver == "function" && name == "prototype") {
                receiver.prototype = mixin(Object.create(receiver.prototype), source.prototype);
            } else {
                descriptors[name] = Object.getOwnPropertyDescriptor(source, name);
            }
        }
    }
    Object.defineProperties(receiver, descriptors);
    return receiver;
}