Generating routes in javascript with Twig and Symfony2

Question

Quite odd problem, sorry for asking, i'm quite new to Symfony/Twig. My route requires a mandatory region_id paramenter:

ajax_provinces_by_region:
  pattern: /ajax/region/{region_id}/provinces
  defaults: {_controller: SWAItaliaInCifreBundle:Ajax:provincesByRegion }
  requirements: {region_in: \d+}

The question is: how can i generate this route based on a select element in javascript (code below)?

The problem is: i can't use path and url helpers from Symfony as they require to specify the region_id parameter (this.value) i can't access because it's a javascript variable (and Twig is compiled server-side).

$(document).ready(function() {
    $('select#regions').change(function(){

        // Make an ajax call to get all region provinces
        $.ajax({
            url: // Generate the route using Twig helper
        });

    });
});

Answer 1

I know it's an old question, but just in case you don't want to install a bundle like FOSJsRoutingBundle, here's a little hack:

var url = '{{ path("yourroute", {'region_id': 'region_id'}) }}'; 
url = url.replace("region_id", this.value);

'region_id' is just used as a placeholder, then you replace it in JS with your actual variable this.value