Rails / Assets pipeline: Dynamically list assets included in a manifest

Question

I'm successfully using assets pipeline for months. Now I would like to load some of my JS files asynchronously (using yepnope library). It works well when config.assets.debug is false.

But in development mode (where config.assets.debug is usually true), the best option for me would be to dynamically get a list of all js files included in my manifests (I got 2 manifests: application.js and externals.js) to give them to yepnope for async loading.

Any idea to do so?

Answer 1

Finally found the answer, I created this helper (read this to see how to declare helper methods visible during asset compilation)

# given a list of Sprockets manifests, returns a flattened array of dependency paths
def paths_for_manifests(manifests = [])
  manifests.map do |manifest|
    Rails.application.assets[manifest].dependencies.map{|d| "/assets/#{d.logical_path}"}
  end.flatten
end

and I use it like this (from a JS / CoffeeScript file):

paths = <%= paths_for_manifests(%w(externals.js application.js)) %>