Generates a set of JavaScript functions that behave very similarly to Rails' named routes. Even plays nice with the assets pipeline.

application.rb

module Sprockets::Helpers::RailsHelper
  require File.join(Rails.root, "app", "helpers", "assets_helper.rb")
  include AssetsHelper
end

assets_helper.rb

module AssetsHelper
  def route_names_with_paths
    # White list of all of the routes.
    allowed_controllers = %w{controllers you want to generate routes for}

    selected_routes = Rails.application.routes.routes.select do |route|
      controller = route.requirements[:controller]
      allowed_controllers.include?(controller)
    end

    # All we really care about is the name and the path.
    selected_routes.inject({}) do |h, r|
      # For whatever reason, it has this special format thinger on the end.
      h[r.name] = r.path.gsub(%r{\(\.:format\)$}, '').strip
      h
    end.to_json.html_safe
  end
end

rails_routes.js

(function(w) {
  function evaluateRouteWithPath(path, params, options) {
    options = options || {}

    var complete = path;
    for(var i in params) {
      var param = params[i];

      if(typeof(param) === 'object') {
        param = param.toParam();
      }
      else if(typeof(param) == 'function') {
        param = param();
      }

      complete = complete.replace(/(\:\w+)/, param);
    }

    if(options.format) {
      complete += '.json';
    }

    return complete;
  }

  var relativeRoute = function(path) {
    return function() {
      var args = Array.prototype.slice.call(arguments);

      // Check options.
      var options = args.pop();

      if(typeof(options) !== 'object') {
        args.push(options);
        options = null;
      }

      return evaluateRouteWithPath(path, arguments);
    };
  };

  var absoluteRoute = function(path) {
    var host = document.location.protocol + '//<%= API_DOMAIN %>' + path;

    return function() {
      var args = Array.prototype.slice.call(arguments);

      // Check options.
      var options = args.pop();

      if(typeof(options) !== 'object') {
        args.push(options);
        options = null;
      }

      return evaluateRouteWithPath(host, args, options);
    }
  };

  var routes = <%= route_names_with_paths %>;
  for(var i in routes) {
    if(typeof(routes[i]) !== 'string') {
      continue;
    }

    window[i + '_path'] = relativeRoute(routes[i]);
    window[i + '_url'] = absoluteRoute(routes[i]);
  }

})(window);