Improve documentation for asset_url

Updated CHANGELOG.md with entry about :host in asset_url

2 files changed, 12 insertions, 1 deletions

diff --git a/actionview/CHANGELOG.md b/actionview/CHANGELOG.md
index a6f6ac78db..36028122d1 100644
--- a/actionview/CHANGELOG.md
+++ b/actionview/CHANGELOG.md
@@ -87,5 +87,9 @@
 
     *Piotr Chmolowski, Łukasz Strzałkowski*
 
+*   Allow custom `:host` option to be passed to `asset_url` helper that
+    overwrites `config.action_controller.asset_host` for particular asset.
+
+    *Hubert Łępicki*
 
 Please check [4-1-stable](https://github.com/rails/rails/blob/4-1-stable/actionview/CHANGELOG.md) for previous changes.
diff --git a/actionview/lib/action_view/helpers/asset_url_helper.rb b/actionview/lib/action_view/helpers/asset_url_helper.rb
index 86a84c1356..ae684af87b 100644
--- a/actionview/lib/action_view/helpers/asset_url_helper.rb
+++ b/actionview/lib/action_view/helpers/asset_url_helper.rb
@@ -147,7 +147,14 @@ module ActionView
 
       # Computes the full URL to an asset in the public directory. This
       # will use +asset_path+ internally, so most of their behaviors
-      # will be the same.
+      # will be the same. If :host options is set, it overwrites global
+      # +config.action_controller.asset_host+ setting.
+      #
+      # All other options provided are forwarded to +asset_path+ call.
+      #
+      #   asset_url "application.js"                                 # => http://example.com/application.js
+      #   asset_url "application.js", host: "http://cdn.example.com" # => http://cdn.example.com/javascripts/application.js
+      #
       def asset_url(source, options = {})
         path_to_asset(source, options.merge(:protocol => :request))
       end