feat: add the ability to filter pages from search (#776)

Co-authored-by: Vince Picone <Vincent.Patrick.Picone@ibm.com>

.eslintrc

@@ -1,9 +1,9 @@
 {
   "extends": ["wesbos"],
   "rules": {
-    "react/prop-types": false,
-    "react/destructuring-assignment": false,
-    "react/no-access-state-in-setstate": false,
+    "react/prop-types": 0,
+    "react/destructuring-assignment": 0,
+    "react/no-access-state-in-setstate": 0,
     "no-useless-escape": 0
   }
 }

packages/example/src/pages/guides/MDX.mdx

@@ -20,13 +20,17 @@ layout.
 ## Frontmatter
 
 You can declare frontmatter in your `.mdx` files to provide specific metadata for the theme to use.
-The most important of which is the `title`. You can also provide a description and keywords which will be added to the `head` of your document.
+- `title`: Main page title: search results and SEO
+- `description`: SEO and search results
+- `keywords`: just SEO (optional)
+- `hiddenFromSearch`: if true, page will be excluded from search
 
 ```md
 ---
 title: Markdown
 description: Usage instructions for the Markdown component
 keywords: 'ibm,carbon,gatsby,mdx,markdown'
+hiddenFromSearch: true
 ---
 ```
 

packages/gatsby-theme-carbon/config/lunr-options.js

@@ -2,7 +2,11 @@ module.exports = {
   languages: [
     {
       name: 'en',
-      filterNodes: node => node.context && node.context.MdxNode,
+      filterNodes: node =>
+        // Lunr let's you filter non-mdx nodes. We only want to filter MDX nodes that aren't hiddenFromSearch
+        node.context &&
+        node.context.MdxNode &&
+        !node.context.frontmatter.hiddenFromSearch,
     },
   ],
   fields: [