Add TailwindCSS purging in production

Author: dixpac

README.md

@@ -12,6 +12,11 @@ This is extraction originally created inside the [tailwindcss-rails](https://git
 1. Run `./bin/bundle add tailwindcss-rails-webpacker`
 2. Run `./bin/rails tailwindcss:install`
 
+## Purging in production
+
+The Tailwind CSS framework starts out as a massive file, which gives you all the combinations of utility classes for development, but you wouldn't want to ship all those unused classes in production.
+
+This gem will automatically purge those unused classes in production.
 
 ## License
 

lib/install/stylesheets/tailwind.config.js

@@ -0,0 +1,19 @@
+module.exports = {
+  // Purge unused TailwindCSS styles
+  purge: {
+    enabled: ["production"].includes(process.env.NODE_ENV),
+    content: [
+      './**/*.html.erb',
+      './app/helpers/**/*.rb',
+      './app/javascript/**/*.js',
+    ],
+  },
+  darkMode: 'media', // or 'media' or 'class'
+  theme: {
+    extend: {},
+  },
+  variants: {
+    extend: {},
+  },
+  plugins: [],
+}

lib/install/tailwindcss.rb

@@ -7,7 +7,6 @@
 
 say "Configuring Tailwind CSS"
 directory Pathname.new(__dir__).join("stylesheets"), Webpacker.config.source_path.join("stylesheets")
-Dir.chdir(WEBPACK_STYLESHEETS_PATH) { run "npx tailwindcss init" }
 
 insert_into_file "postcss.config.js", "require('tailwindcss')(\"./app/javascript/stylesheets/tailwind.config.js\"),\n    ",
                  before: "require('postcss-import')"