feat: add last updated date to blog posts

.eleventy.js

@@ -23,6 +23,7 @@ const fs = require("node:fs");
 const yaml = require("js-yaml");
 const { DateTime } = require("luxon");
 const preWrapperPlugin = require("./src/_11ty/plugins/pre-wrapper.js");
+const blogDates = require("./src/_data/blog-dates.json");
 
 //-----------------------------------------------------------------------------
 // Eleventy Config
@@ -160,6 +161,20 @@ module.exports = eleventyConfig => {
 		value1.concat(value2),
 	);
 
+	eleventyConfig.addFilter("lastUpdated", filepath => {
+		const relativePath = path.relative("src/content/blog", filepath);
+		const isoDate = blogDates[relativePath];
+		const cutoffDate = new Date("2022-08-01");
+
+		if (!isoDate) {
+			return null;
+		}
+
+		const publishDate = new Date(relativePath.slice(0, 10));
+		const date = new Date(isoDate);
+		return publishDate > cutoffDate ? date : null;
+	});
+
 	/**
 	 * ***************************************************************************************
 	 *  Plugins

package.json

@@ -15,6 +15,7 @@
   "license": "Apache-2.0",
   "scripts": {
     "build": "npm-run-all install:playground build:sass build:website build:playground build:minify-images",
+    "build:init-blog-dates": "node tools/update-blog-dates.js --init",
     "build:minify-images": "imagemin '_site/assets/images' --out-dir='_site/assets/images'",
     "build:minify-svg": "svgo -r -f ./",
     "build:playground": "webpack --mode=production --progress",
@@ -53,6 +54,10 @@
     ],
     "*.json": "prettier --write",
     "*.md": "markdownlint --fix",
+    "src/content/blog/*.md": [
+      "node tools/update-blog-dates.js",
+      "git add src/_data/blog-dates.json"
+    ],
     "**/*.svg": "npx svgo -r --multipass"
   },
   "gitHooks": {