Rule: Add form-method-require rule

.editorconfig

@@ -6,12 +6,9 @@ root = true
 
 # Apply for all files
 [*]
-
 charset = utf-8
-
 indent_style = space
 indent_size = 2
-
 end_of_line = lf
 insert_final_newline = true
 trim_trailing_whitespace = true

.gitignore

@@ -1,17 +1,12 @@
 # Files that might appear in the root of a volume
 .DocumentRevisions-V100
-.fseventsd
 .Spotlight-V100
 .TemporaryItems
 .Trashes
-.VolumeIcon.icns
-.com.apple.timemachine.donotpresent
 
 # Editor directories and files
 .idea
 *.suo
-*.ntvs*
-*.njsproj
 *.sln
 
 # Generated files
@@ -25,13 +20,9 @@ yarn-debug.log*
 yarn-error.log*
 
 # Runtime data
-pids
 *.pid
 *.seed
 
-# Directory for instrumented libs generated by jscoverage/JSCover
-lib-cov
-
 # Coverage directory used by tools like nyc and istanbul
 .nyc_output
 coverage
@@ -44,9 +35,6 @@ build/Release
 # https://www.npmjs.org/doc/misc/npm-faq.html#should-i-check-my-node_modules-folder-into-git-
 node_modules
 
-# Users Environment Variables
-.lock-wscript
-
 # macOS
 *.DS_Store
 .AppleDouble

src/core/rules/form-method-require.ts

@@ -0,0 +1,45 @@
+import { Listener } from '../htmlparser'
+import { Rule } from '../types'
+
+export default {
+  id: 'form-method-require',
+  description:
+    'The method attribute of a <form> element must be present with a valid value: "get", "post", or "dialog".',
+  init(parser, reporter) {
+    const onTagStart: Listener = (event) => {
+      const tagName = event.tagName.toLowerCase()
+
+      if (tagName === 'form') {
+        const mapAttrs = parser.getMapAttrs(event.attrs)
+        const col = event.col + tagName.length + 1
+
+        if (mapAttrs.method === undefined) {
+          reporter.warn(
+            'The method attribute must be present on <form> elements.',
+            event.line,
+            col,
+            this,
+            event.raw
+          )
+        } else {
+          const methodValue = mapAttrs.method.toLowerCase()
+          if (
+            methodValue !== 'get' &&
+            methodValue !== 'post' &&
+            methodValue !== 'dialog'
+          ) {
+            reporter.warn(
+              'The method attribute of <form> must have a valid value: "get", "post", or "dialog".',
+              event.line,
+              col,
+              this,
+              event.raw
+            )
+          }
+        }
+      }
+    }
+
+    parser.addListener('tagstart', onTagStart)
+  },
+} as Rule

src/core/rules/index.ts

@@ -13,6 +13,7 @@ export { default as buttonTypeRequire } from './button-type-require'
 export { default as doctypeFirst } from './doctype-first'
 export { default as doctypeHTML5 } from './doctype-html5'
 export { default as emptyTagNotSelfClosed } from './empty-tag-not-self-closed'
+export { default as formMethodRequire } from './form-method-require'
 export { default as frameTitleRequire } from './frame-title-require'
 export { default as h1Require } from './h1-require'
 export { default as headScriptDisabled } from './head-script-disabled'

src/core/types.ts

@@ -22,6 +22,7 @@ export interface Ruleset {
   'doctype-first'?: boolean
   'doctype-html5'?: boolean
   'empty-tag-not-self-closed'?: boolean
+  'form-method-require'?: boolean
   'head-script-disabled'?: boolean
   'href-abs-or-rel'?: 'abs' | 'rel'
   'id-class-ad-disabled'?: boolean

test/rules/form-method-require.spec.js

@@ -0,0 +1,64 @@
+const HTMLHint = require('../../dist/htmlhint.js').HTMLHint
+
+const ruleId = 'form-method-require'
+const ruleOptions = {}
+
+ruleOptions[ruleId] = true
+
+describe(`Rules: ${ruleId}`, () => {
+  it('Form with method="get" should not result in an error', () => {
+    const code = '<form method="get"></form>'
+    const messages = HTMLHint.verify(code, ruleOptions)
+    expect(messages.length).toBe(0)
+  })
+
+  it('Form with method="post" should not result in an error', () => {
+    const code = '<form method="post"></form>'
+    const messages = HTMLHint.verify(code, ruleOptions)
+    expect(messages.length).toBe(0)
+  })
+
+  it('Form with method="dialog" should not result in an error', () => {
+    const code = '<form method="dialog"></form>'
+    const messages = HTMLHint.verify(code, ruleOptions)
+    expect(messages.length).toBe(0)
+  })
+
+  it('Form without method attribute should result in an error', () => {
+    const code = '<form></form>'
+    const messages = HTMLHint.verify(code, ruleOptions)
+    expect(messages.length).toBe(1)
+    expect(messages[0].rule.id).toBe(ruleId)
+    expect(messages[0].line).toBe(1)
+    expect(messages[0].col).toBe(6)
+    expect(messages[0].type).toBe('warning')
+    expect(messages[0].message).toBe(
+      'The method attribute must be present on <form> elements.'
+    )
+  })
+
+  it('Form with invalid method value should result in an error', () => {
+    const code = '<form method="invalid"></form>'
+    const messages = HTMLHint.verify(code, ruleOptions)
+    expect(messages.length).toBe(1)
+    expect(messages[0].rule.id).toBe(ruleId)
+    expect(messages[0].line).toBe(1)
+    expect(messages[0].col).toBe(6)
+    expect(messages[0].type).toBe('warning')
+    expect(messages[0].message).toBe(
+      'The method attribute of <form> must have a valid value: "get", "post", or "dialog".'
+    )
+  })
+
+  it('Form with uppercase method value should not result in an error', () => {
+    const code = '<form method="POST"></form>'
+    const messages = HTMLHint.verify(code, ruleOptions)
+    expect(messages.length).toBe(0)
+  })
+
+  it('Other elements should not be affected by this rule', () => {
+    const code = '<div>Not a form</div><input type="text">'
+    const messages = HTMLHint.verify(code, ruleOptions)
+    expect(messages.length).toBe(0)
+  })
+})

website/astro.config.mjs

@@ -70,6 +70,8 @@ export default defineConfig({
           attrs: {
             rel: 'manifest',
             href: '/site.webmanifest',
+            crossorigin: 'use-credentials',
+            fetchpriority: 'low',
           },
         },
         {

website/src/content/docs/rules/form-method-require.mdx

@@ -0,0 +1,47 @@
+---
+id: form-method-require
+title: form-method-require
+description: Requires form elements to have a valid method attribute for better security and user experience.
+sidebar:
+  badge: New
+  hidden: true
+pagefind: false
+---
+
+import { Badge } from '@astrojs/starlight/components';
+
+The method attribute of a `<form>` element must be present with a valid value: "get", "post", or "dialog".
+
+Level: <Badge text="Warning" variant="caution" />
+
+## Config value
+
+- `true`: enable rule
+- `false`: disable rule
+
+### The following patterns are **not** considered rule violations
+
+```html
+<form method="get"></form>
+<form method="post"></form>
+<form method="dialog"></form>
+```
+
+### The following patterns are considered rule violations
+
+```html
+<form>No method specified</form>
+<form method="invalid">Invalid method</form>
+```
+
+## Why this rule is important
+
+The absence of the method attribute means the form will use the default `GET` method. With `GET`, form data is included in the URL (e.g., `?username=john&password=secret`), which can expose sensitive information in browser history, logs, or the network request.
+
+The HTML specification requires that form elements have one of three valid methods:
+
+- `get`: Appends form data to the URL (default, but not recommended for sensitive data)
+- `post`: Sends form data in the request body (more secure for sensitive data)
+- `dialog`: Used for dialog forms (HTML5 feature)
+
+This rule helps ensure that forms have explicit, valid methods for better security and user experience.