feat: add JSON frontmatter support to no-multiple-h1 rule

Author: Pixel998

docs/rules/no-multiple-h1.md

@@ -12,7 +12,7 @@ This rule warns when it finds more than one H1 heading in a Markdown document. I
 
 - ATX-style headings (`# Heading`)
 - Setext-style headings (`Heading\n=========`)
-- Front matter title fields (YAML and TOML)
+- Front matter title fields (YAML, TOML, and JSON)
 - HTML h1 tags (`<h1>Heading</h1>`)
 
 Examples of **incorrect** code for this rule:
@@ -46,7 +46,7 @@ Another H1 heading
 
 The following options are available on this rule:
 
-* `frontmatterTitle: string` - A regex pattern to match title fields in front matter. The default pattern matches both YAML (`title:`) and TOML (`title =`) formats. Set to an empty string to disable front matter title checking.
+* `frontmatterTitle: string` - A regex pattern to match title fields in front matter. The default pattern matches YAML (`title:`), TOML (`title =`), and JSON (`"title":`) formats. Set to an empty string to disable front matter title checking.
 
 Examples of **incorrect** code for this rule:
 

src/rules/no-multiple-h1.js

@@ -98,6 +98,12 @@ export default {
 				}
 			},
 
+			json(node) {
+				if (frontmatterHasTitle(node.value, titlePattern)) {
+					h1Count++;
+				}
+			},
+
 			html(node) {
 				let match;
 				while ((match = h1TagPattern.exec(node.value)) !== null) {

tests/rules/no-multiple-h1.test.js

@@ -82,6 +82,19 @@ ruleTester.run("no-multiple-h1", rule, {
 				frontmatter: "toml",
 			},
 		},
+		{
+			code: dedent`
+				---
+				{
+					"title": "My Title"
+				}
+				---
+				## Heading 2
+			`,
+			languageOptions: {
+				frontmatter: "json",
+			},
+		},
 		{
 			code: dedent`
 				---
@@ -150,6 +163,20 @@ ruleTester.run("no-multiple-h1", rule, {
 				frontmatter: "toml",
 			},
 		},
+		{
+			code: dedent`
+				---
+				{
+					"heading": "My Title"
+				}
+				---
+				## Heading 2
+			`,
+			options: [{ frontmatterTitle: '^\\s*"heading"\\s*:' }],
+			languageOptions: {
+				frontmatter: "json",
+			},
+		},
 		{
 			code: dedent`
 				---
@@ -172,6 +199,19 @@ ruleTester.run("no-multiple-h1", rule, {
 				frontmatter: "toml",
 			},
 		},
+		{
+			code: dedent`
+				---
+				{
+					"author": "Pixel998"
+				}
+				---
+				# Heading 1
+			`,
+			languageOptions: {
+				frontmatter: "json",
+			},
+		},
 		{
 			code: dedent`
 				---
@@ -196,6 +236,20 @@ ruleTester.run("no-multiple-h1", rule, {
 				frontmatter: "toml",
 			},
 		},
+		{
+			code: dedent`
+				---
+				{
+					"title": "My Title"
+				}
+				---
+				# Heading 1
+			`,
+			options: [{ frontmatterTitle: "" }],
+			languageOptions: {
+				frontmatter: "json",
+			},
+		},
 		'<h1 class="title">Heading</h1>',
 		dedent`
 			# Heading 1
@@ -422,6 +476,28 @@ ruleTester.run("no-multiple-h1", rule, {
 				},
 			],
 		},
+		{
+			code: dedent`
+				---
+				{
+					"title": "My Title"
+				}
+				---
+				# Heading 1
+			`,
+			languageOptions: {
+				frontmatter: "json",
+			},
+			errors: [
+				{
+					messageId: "multipleH1",
+					line: 6,
+					column: 1,
+					endLine: 6,
+					endColumn: 12,
+				},
+			],
+		},
 		{
 			code: dedent`
 				---
@@ -462,6 +538,28 @@ ruleTester.run("no-multiple-h1", rule, {
 				},
 			],
 		},
+		{
+			code: dedent`
+				---
+				{
+					'title': 'My Title'
+				}
+				---
+				# Heading 1
+			`,
+			languageOptions: {
+				frontmatter: "json",
+			},
+			errors: [
+				{
+					messageId: "multipleH1",
+					line: 6,
+					column: 1,
+					endLine: 6,
+					endColumn: 12,
+				},
+			],
+		},
 		{
 			code: dedent`
 				---
@@ -504,6 +602,29 @@ ruleTester.run("no-multiple-h1", rule, {
 				},
 			],
 		},
+		{
+			code: dedent`
+				---
+				{
+					"author": "Pixel998"
+					"title": "My Title"
+				}
+				---
+				# Heading 1
+			`,
+			languageOptions: {
+				frontmatter: "json",
+			},
+			errors: [
+				{
+					messageId: "multipleH1",
+					line: 7,
+					column: 1,
+					endLine: 7,
+					endColumn: 12,
+				},
+			],
+		},
 		{
 			code: dedent`
 				---
@@ -544,6 +665,28 @@ ruleTester.run("no-multiple-h1", rule, {
 				},
 			],
 		},
+		{
+			code: dedent`
+				---
+				{
+					"TITLE": "My Title"
+				}
+				---
+				# Heading 1
+			`,
+			languageOptions: {
+				frontmatter: "json",
+			},
+			errors: [
+				{
+					messageId: "multipleH1",
+					line: 6,
+					column: 1,
+					endLine: 6,
+					endColumn: 12,
+				},
+			],
+		},
 		{
 			code: dedent`
 				---
@@ -586,6 +729,29 @@ ruleTester.run("no-multiple-h1", rule, {
 				},
 			],
 		},
+		{
+			code: dedent`
+				---
+				{
+					"heading": "My Title"
+				}
+				---
+				# Heading 1
+			`,
+			options: [{ frontmatterTitle: '^\\s*"heading"\\s*:' }],
+			languageOptions: {
+				frontmatter: "json",
+			},
+			errors: [
+				{
+					messageId: "multipleH1",
+					line: 6,
+					column: 1,
+					endLine: 6,
+					endColumn: 12,
+				},
+			],
+		},
 		{
 			code: dedent`
 				---
@@ -630,6 +796,30 @@ ruleTester.run("no-multiple-h1", rule, {
 				},
 			],
 		},
+		{
+			code: dedent`
+				---
+				{
+					"title": "My Title"
+				}
+				---
+				# Heading 1
+				# Another H1
+			`,
+			options: [{ frontmatterTitle: "" }],
+			languageOptions: {
+				frontmatter: "json",
+			},
+			errors: [
+				{
+					messageId: "multipleH1",
+					line: 7,
+					column: 1,
+					endLine: 7,
+					endColumn: 13,
+				},
+			],
+		},
 		{
 			code: dedent`
 				<h1>Heading</h1>
@@ -769,5 +959,36 @@ ruleTester.run("no-multiple-h1", rule, {
 				},
 			],
 		},
+		{
+			code: dedent`
+				---
+				{
+					"title": "My Title"
+				}
+				---
+				# Heading 1
+				
+				<h1>Another H1</h1>
+			`,
+			languageOptions: {
+				frontmatter: "json",
+			},
+			errors: [
+				{
+					messageId: "multipleH1",
+					line: 6,
+					column: 1,
+					endLine: 6,
+					endColumn: 12,
+				},
+				{
+					messageId: "multipleH1",
+					line: 8,
+					column: 1,
+					endLine: 8,
+					endColumn: 20,
+				},
+			],
+		},
 	],
 });