[html] Add documentation (#3885)

docs/_data/sidebars/pmd_sidebar.yml

@@ -379,6 +379,9 @@ entries:
     - title: XML and XML dialects
       url: /pmd_languages_xml.html
       output: web, pdf
+    - title: HTML
+      url: /pmd_languages_html.html
+      output: web, pdf
   - title: Developer Documentation
     output: web, pdf
     folderitems:

docs/pages/pmd/languages/html.md

@@ -0,0 +1,18 @@
+---
+title: Processing HTML files
+permalink: pmd_languages_html.html
+last_updated: April 2022 (6.45.0)
+---
+
+## The HTML language module
+
+**Since:** 6.45.0
+
+**Minimum Java Runtime:** Java 8
+
+{% include warning.html content="This language module is experimental and may change any time." %}
+
+The HTML language module uses [jsoup](https://jsoup.org/) for parsing.
+
+XPath rules are supported, but the DOM is not a typical XML/XPath DOM. E.g.
+text nodes are normal nodes. This might change in the future.

docs/pages/release_notes.md

@@ -14,6 +14,36 @@ This is a {{ site.pmd.release_type }} release.
 
 ### New and noteworthy
 
+#### Support for HTML
+
+This version of PMD ships a new language module to support analyzing of HTML.
+Support for HTML is experimental and might change without notice.
+
+#### New rules
+
+* The HTML rule {% rule html/bestpractices/AvoidInlineStyles %} finds elements which use a style attribute.
+  In order to help maintaining a webpage it is considered good practice to separate content and styles. Instead
+  of inline styles one should use CSS files and classes.
+
+```xml
+    <rule ref="category/html/bestpractices.xml/AvoidInlineStyles" />
+```
+
+* The HTML rule {% rule html/bestpractices/UnnecessaryTypeAttribute %} finds "link" and "script" elements which
+  still have a "type" attribute. This is not necessary anymore since modern browsers automatically use CSS and
+  JavaScript.
+
+```xml
+      <rule ref="category/html/bestpractices.xml/UnnecessaryTypeAttribute" />
+```
+
+* The HTML rule {% rule html/bestpractices/UseAltAttributeForImages %} finds "img" elements without an "alt"
+  attribute. An alternate text should always be provided in order to help screen readers.
+
+```xml
+      <rule ref="category/html/bestpractices.xml/UseAltAttributeForImages" />
+```
+
 #### Modified rules
 
 *   The Java rule {% rule java/bestpractices/UnusedPrivateField %} has a new property `ignoredFieldNames`.

pmd-core/src/main/resources/rulesets/releases/6450.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0"?>
+
+<ruleset name="6450"
+    xmlns="http://pmd.sourceforge.net/ruleset/2.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 https://pmd.sourceforge.io/ruleset_2_0_0.xsd">
+  <description>
+This ruleset contains links to rules that are new in PMD v6.45.0
+  </description>
+
+    <rule ref="category/html/bestpractices.xml/AvoidInlineStyles" />
+    <rule ref="category/html/bestpractices.xml/UnnecessaryTypeAttribute" />
+    <rule ref="category/html/bestpractices.xml/UseAltAttributeForImages" />
+
+</ruleset>