Can anyone suggest a good client-side architecture and structure for large scale web applications?

I'm building a large scale web application. It will grow in the future so I need a good back-end and front-end architecture for my application. at the back of the site, I use Zend Framework so the architecture is OK for me. But at the front, working with javascript and ajax without having a good architecture makes later changes hard and confusing.

For now, I'm using my own architecture. I have a big object for the whole application say BigObject. I extend it when modules are added to the site. say I have an upload module. I use this:

BigObject.upload={
    //initialization
    init:function(){
    },
    //I tried to use what I named semi-MVC architecture!!!
    controllers:{
        //index is a controller
        someController:{
            init:function(){
                //initialization
            },
            someAction:function(){
                //Code goes here
                //call a model if necessary
                //call view script
                BigObject.upload.views.someController.someAction();
            }
        }
    },
    models:{
        //models required for this module like loading contents with ajax.
        loadContent:function(part,callback){
        }
    }
    views:{
        init:function(){
            //initialize view
        },
        someController:{
            someAction:function(){
            }
        }
    }
}

What do you think? Is there any better solution to this problem? anyone thought about a good structure for front-end part of web applications ( like what we have at back-end,good file structure and object-oriented methods )?

from Can anyone suggest a good client-side architecture and structure for large scale web applications?