Merge pull request #40092 from fleck/dont-push-assets-and-skip-preload-for-defer-javascript

don't add preload headers for deferred scripts and add nopush

actionview/lib/action_view/helpers/asset_tag_helper.rb

@@ -87,10 +87,15 @@ def javascript_include_tag(*sources)
         options = sources.extract_options!.stringify_keys
         path_options = options.extract!("protocol", "extname", "host", "skip_pipeline").symbolize_keys
         preload_links = []
+        nopush = options["nopush"].nil? ? true : options.delete("nopush")
 
         sources_tags = sources.uniq.map { |source|
           href = path_to_javascript(source, path_options)
-          preload_links << "<#{href}>; rel=preload; as=script"
+          unless options["defer"]
+            preload_link = "<#{href}>; rel=preload; as=script"
+            preload_link += "; nopush" if nopush
+            preload_links << preload_link
+          end
           tag_options = {
             "src" => href
           }.merge!(options)
@@ -137,10 +142,13 @@ def stylesheet_link_tag(*sources)
         options = sources.extract_options!.stringify_keys
         path_options = options.extract!("protocol", "host", "skip_pipeline").symbolize_keys
         preload_links = []
+        nopush = options["nopush"].nil? ? true : options.delete("nopush")
 
         sources_tags = sources.uniq.map { |source|
           href = path_to_stylesheet(source, path_options)
-          preload_links << "<#{href}>; rel=preload; as=style"
+          preload_link = "<#{href}>; rel=preload; as=style"
+          preload_link += "; nopush" if nopush
+          preload_links << preload_link
           tag_options = {
             "rel" => "stylesheet",
             "media" => "screen",

actionview/test/template/asset_tag_helper_test.rb

@@ -513,6 +513,18 @@ def test_javascript_include_tag_without_request
   def test_should_set_preload_links
     stylesheet_link_tag("http://example.com/style.css")
     javascript_include_tag("http://example.com/all.js")
+    expected = "<http://example.com/style.css>; rel=preload; as=style; nopush,<http://example.com/all.js>; rel=preload; as=script; nopush"
+    assert_equal expected, @response.headers["Link"]
+  end
+
+  def test_should_not_preload_links_with_defer
+    javascript_include_tag("http://example.com/all.js", defer: true)
+    assert_equal "", @response.headers["Link"]
+  end
+
+  def test_should_allow_caller_to_remove_nopush
+    stylesheet_link_tag("http://example.com/style.css", nopush: false)
+    javascript_include_tag("http://example.com/all.js", nopush: false)
     expected = "<http://example.com/style.css>; rel=preload; as=style,<http://example.com/all.js>; rel=preload; as=script"
     assert_equal expected, @response.headers["Link"]
   end