gistfile1.js

function get_gni_data( options ) {
    alert( options.search_term );
    alert( options.add_register_link ); 

    // defaults are annoying. You could do something like this:
    options.search_term = options.search_term || "some default";

    // OR if you're using a library like Underscore, you could do 

    options = _({ search_term: "default_value", add_regsiter_link: 1}).extend( options );

}

// to call it: 
get_gni_data({ 
  search_term: search_term,
  add_register_link: 0
});