3 files changed, 37 insertions, 0 deletions
diff --git a/actionview/lib/action_view/helpers.rb b/actionview/lib/action_view/helpers.rb
index 46f20c4277..8cc8013718 100644
--- a/actionview/lib/action_view/helpers.rb
+++ b/actionview/lib/action_view/helpers.rb
@@ -13,6 +13,7 @@ module ActionView #:nodoc:
     autoload :CacheHelper
     autoload :CaptureHelper
     autoload :ControllerHelper
+    autoload :CspHelper
     autoload :CsrfHelper
     autoload :DateHelper
     autoload :DebugHelper
@@ -46,6 +47,7 @@ module ActionView #:nodoc:
     include CacheHelper
     include CaptureHelper
     include ControllerHelper
+    include CspHelper
     include CsrfHelper
     include DateHelper
     include DebugHelper
diff --git a/actionview/lib/action_view/helpers/csp_helper.rb b/actionview/lib/action_view/helpers/csp_helper.rb
new file mode 100644
index 0000000000..e2e065c218
--- /dev/null
+++ b/actionview/lib/action_view/helpers/csp_helper.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+module ActionView
+  # = Action View CSP Helper
+  module Helpers #:nodoc:
+    module CspHelper
+      # Returns a meta tag "csp-nonce" with the per-session nonce value
+      # for allowing inline <script> tags.
+      #
+      #   <head>
+      #     <%= csp_meta_tag %>
+      #   </head>
+      #
+      # This is used by the Rails UJS helper to create dynamically
+      # loaded inline <script> elements.
+      #
+      def csp_meta_tag
+        if content_security_policy?
+          tag("meta", name: "csp-nonce", content: content_security_policy_nonce)
+        end
+      end
+    end
+  end
+end
diff --git a/actionview/lib/action_view/helpers/javascript_helper.rb b/actionview/lib/action_view/helpers/javascript_helper.rb
index dd2cd57ac3..acc50f8a62 100644
--- a/actionview/lib/action_view/helpers/javascript_helper.rb
+++ b/actionview/lib/action_view/helpers/javascript_helper.rb
@@ -63,6 +63,13 @@ module ActionView
       #   <%= javascript_tag defer: 'defer' do -%>
       #     alert('All is good')
       #   <% end -%>
+      #
+      # If you have a content security policy enabled then you can add an automatic
+      # nonce value by passing +nonce: true+ as part of +html_options+. Example:
+      #
+      #   <%= javascript_tag nonce: true do -%>
+      #     alert('All is good')
+      #   <% end -%>
       def javascript_tag(content_or_options_with_block = nil, html_options = {}, &block)
         content =
           if block_given?
@@ -72,6 +79,10 @@ module ActionView
             content_or_options_with_block
           end
 
+        if html_options[:nonce] == true
+          html_options[:nonce] = content_security_policy_nonce
+        end
+
         content_tag("script".freeze, javascript_cdata_section(content), html_options)
       end