Passing url dynamically to the filebrowser button in ckeditor

I am customizing the functionality of ckeditor image upload. The user sees a dropdown with different options. Depending upon the option selected from the dropdown the "Browse Server" button should take the user to corresponding url.

So basically I need to dynamically pass the browse server url (which has chosen from a drop down list) to the filebrowser of Image Upload functionality of CK Editor 3.4.1 gem.

Example:

I am having a select box in the Image Info Tab for that I have added the following code.

           {
                type : 'select',
                id : 'url_path',
                items :
                [
                [ 'Add photos from My Computer', '' ],
                [ 'Add photos from My Album', 'http://localhost:3000/pages/'],
                ],
                onChange:function(){
                    L=this.getValue();

              }

Browse Button code looks like this

            {
                        type:'button',
                        id:'browse',
                        style:'display:inline-block;',
                        align:'center',
                        label:b.lang.common.browseServer,
                        hidden:true,
                        filebrowser :
                        {
                        开发者_开发技巧    action : 'Browse',
                            url : '',
                            target : 'info:txtUrl'
                        }

            }

Here the url value has to set according to the value of select box. How can I configure that ?

Regards, Pankaj