Patch GovukTechDocs::TechDocsHTMLRenderer

Add a new `preprocess` hook to the Redcarpet renderer to reset the ID generator.

config.rb

@@ -1,6 +1,11 @@
 require "govuk_tech_docs"
 require "lib/sassdocs_helpers"
 
+# Patch the GovukTechDocs cleanly
+# https://www.justinweiss.com/articles/3-ways-to-monkey-patch-without-making-a-mess/
+require "lib/ext/govuk_tech_docs/tech_docs_html_renderer/reset_unique_identifier_generator_preprocess"
+GovukTechDocs::TechDocsHTMLRenderer.include Ext::GovukTechDocs::TechDocsHTMLRenderer::ResetUniqueIndentifierGeneratorPreprocess
+
 config[:build_dir] = "deploy/public"
 
 GovukTechDocs.configure(self)

lib/ext/govuk_tech_docs/tech_docs_html_renderer/reset_unique_identifier_generator_preprocess.rb

@@ -0,0 +1,25 @@
+module Ext
+  module GovukTechDocs
+    module TechDocsHTMLRenderer
+      module ResetUniqueIndentifierGeneratorPreprocess
+        ##
+        # Fix for the unique ID generation not being reset for each document
+        # leading to IDs being considered duplicates when on different pages
+        # while they shouldn't be
+        # 
+        # @see https://github.com/alphagov/tech-docs-gem/issues/310
+
+        def preprocess(document)
+          ##
+          # Resets the UniqueIdentifierGenerator before the document gets processed
+          #
+          # @see https://github.com/vmg/redcarpet#prepost-process
+
+          ::GovukTechDocs::UniqueIdentifierGenerator.instance.reset
+
+          return document
+        end
+      end
+    end
+  end
+end

source/javascript-api-reference/index.html.md.erb

@@ -30,7 +30,7 @@ GOVUKFrontend.initAll({
 })
 ```
 
-## Accordion component
+## Accordion
 
 ### i18n
 
@@ -117,7 +117,7 @@ Default:
 "Show this section"
 ```
 
-## Button component
+## Button
 
 ### preventDoubleClick
 
@@ -131,7 +131,7 @@ Default:
 false
 ```
 
-## CharacterCount component
+## CharacterCount
 
 ### maxlength
 
@@ -287,7 +287,7 @@ Default:
 }
 ```
 
-## ErrorSummary component
+## ErrorSummary
 
 ### disableAutoFocus
 
@@ -301,7 +301,7 @@ Default
 false
 ```
 
-## NotificationBanner component
+## NotificationBanner
 
 ### `disableAutoFocus`