Support JSON front matter as used by the Hugo site generator (fixes #270).

README.md

@@ -429,11 +429,12 @@ ignores common forms of "front matter". To match differently, specify a custom
 The default value:
 
 ```js
-/((^---\s*$[^]*?^---\s*$)|(^\+\+\+\s*$[^]*?^(\+\+\+|\.\.\.)\s*$))(\r\n|\r|\n|$)/m
+/((^---\s*$[^]*?^---\s*$)|(^\+\+\+\s*$[^]*?^(\+\+\+|\.\.\.)\s*$)|(^\{\s*$[^]*?^\}\s*$))(\r\n|\r|\n|$)/m
 ```
 
-Ignores [YAML](https://en.wikipedia.org/wiki/YAML) and
-[TOML](https://en.wikipedia.org/wiki/TOML) such as:
+Ignores [YAML](https://en.wikipedia.org/wiki/YAML),
+[TOML](https://en.wikipedia.org/wiki/TOML), and
+[JSON](https://en.wikipedia.org/wiki/JSON) front matter such as:
 
 ```text
 ---

doc/Rules.md

@@ -848,7 +848,7 @@ Tags: headings, headers
 
 Aliases: single-title, single-h1
 
-Parameters: level, front_matter_title (number; default 1, string; default "^\s*title:")
+Parameters: level, front_matter_title (number; default 1, string; default "^\s*"?title"?\s*[:=]")
 
 This rule is triggered when a top level heading is in use (the first line of
 the file is a h1 heading), and more than one h1 heading is in use in the
@@ -1565,7 +1565,7 @@ Tags: headings, headers
 
 Aliases: first-line-heading, first-line-h1
 
-Parameters: level, front_matter_title (number; default 1, string; default "^\s*title:")
+Parameters: level, front_matter_title (number; default 1, string; default "^\s*"?title"?\s*[:=]")
 
 This rule is intended to ensure documents have a title and is triggered when
 the first line in the file isn't a top level (h1) heading:

helpers/helpers.js

@@ -12,7 +12,7 @@ module.exports.newLineRe = newLineRe;
 // Regular expression for matching common front matter (YAML and TOML)
 module.exports.frontMatterRe =
   // eslint-disable-next-line max-len
-  /((^---\s*$[^]*?^---\s*$)|(^\+\+\+\s*$[^]*?^(\+\+\+|\.\.\.)\s*$))(\r\n|\r|\n|$)/m;
+  /((^---\s*$[^]*?^---\s*$)|(^\+\+\+\s*$[^]*?^(\+\+\+|\.\.\.)\s*$)|(^\{\s*$[^]*?^\}\s*$))(\r\n|\r|\n|$)/m;
 
 // Regular expression for matching inline disable/enable comments
 const inlineCommentRe =
@@ -502,7 +502,10 @@ module.exports.frontMatterHasTitle =
     const ignoreFrontMatter =
       (frontMatterTitlePattern !== undefined) && !frontMatterTitlePattern;
     const frontMatterTitleRe =
-      new RegExp(String(frontMatterTitlePattern || "^\\s*title\\s*[:=]"), "i");
+      new RegExp(
+        String(frontMatterTitlePattern || "^\\s*\"?title\"?\\s*[:=]"),
+        "i"
+      );
     return !ignoreFrontMatter &&
       frontMatterLines.some((line) => frontMatterTitleRe.test(line));
   };

test/front-matter-alt-title-json.json

@@ -0,0 +1,6 @@
+{
+  "default": true,
+  "MD041": {
+    "front_matter_title": "^\\s*\"alternate\"\\s*:"
+  }
+}

test/front-matter-alt-title-json.md

@@ -0,0 +1,6 @@
+{
+"date": "2017-01-26T22:17:00+02:00",
+"alternate": "My document title and heading"
+}
+
+Some plain text here.

test/front-matter-title-json-spaces.json

@@ -0,0 +1,4 @@
+{
+  "default": true,
+  "MD041": true
+}

test/front-matter-title-json-spaces.md

@@ -0,0 +1,6 @@
+{
+"date": "2017-01-26T22:17:00+02:00",
+"title": "My document title and heading"
+}   
+
+Some plain text here.

test/front-matter-title-json.json

@@ -0,0 +1,4 @@
+{
+  "default": true,
+  "MD041": true
+}

test/front-matter-title-json.md

@@ -0,0 +1,6 @@
+{
+"date": "2017-01-26T22:17:00+02:00",
+"title": "My document title and heading"
+}
+
+Some plain text here.

test/hugo-quickstart-example-json.json

@@ -0,0 +1,4 @@
+{
+  "default": true,
+  "MD041": true
+}

test/hugo-quickstart-example-json.md

@@ -0,0 +1,13 @@
+{
+    "title": "Another Hugo Post",
+    "description": "Nothing special, but one post is boring.",
+    "date": "2014-09-02",
+    "categories": [ "example", "configuration" ],
+    "tags": [
+        "example",
+        "hugo",
+        "toml"
+    ],
+}
+
+# Heading {MD025}