Use Knip to detect dead code

Author: alexeyr

.eslintrc

@@ -4,6 +4,7 @@ extends:
   - prettier/react
 
 plugins:
+  - import
   - prettier
 
 globals:

.github/workflows/main.yml

@@ -71,7 +71,7 @@ jobs:
     - name: generate file system-based packs
       run: cd spec/dummy && RAILS_ENV=test bundle exec rake react_on_rails:generate_packs
     - name: Build test bundles for dummy app
-      run: cd spec/dummy && rm -rf public/webpack/test && yarn build:rescript && RAILS_ENV=test NODE_ENV=test bin/${{ matrix.versions == 'oldest' && 'web' || 'shaka' }}packer
+      run: cd spec/dummy && rm -rf public/webpack/test && yarn run build:rescript && RAILS_ENV=test NODE_ENV=test bin/${{ matrix.versions == 'oldest' && 'web' || 'shaka' }}packer
     - id: get-sha
       run: echo "::set-output name=sha::$(git rev-parse HEAD)"
     - name: Save test webpack bundles to cache (for build number checksum used by rspec job)

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    react_on_rails (14.1.0)
+    react_on_rails (14.1.1)
       addressable
       connection_pool
       execjs (~> 2.5)

knip.ts

@@ -0,0 +1,24 @@
+import type { KnipConfig } from 'knip';
+
+const config: KnipConfig = {
+  // ! at the end means files are used in production
+  entry: ['node_package/src/ReactOnRails.ts!', 'node_package/src/ReactOnRails.node.ts!'],
+  project: ['node_package/src/**/*.[jt]s!', 'node_package/tests/**/*.[jt]s'],
+  ignoreBinaries: [
+    // Knip fails to detect it's declared in devDependencies
+    'nps',
+    // local scripts
+    'node_package/scripts/.*',
+  ],
+  ignoreDependencies: [
+    // Required for TypeScript compilation, but we don't depend on Turbolinks itself.
+    '@types/turbolinks',
+    // used in package-scripts.yml
+    'concurrently',
+  ],
+  babel: {
+    config: ['node_package/babel.config.js', 'package.json'],
+  },
+};
+
+export default config;

node_package/src/buildConsoleReplay.ts

@@ -9,6 +9,7 @@ declare global {
   }
 }
 
+/** @internal Exported only for tests */
 export function consoleReplay(customConsoleHistory: typeof console['history'] | undefined = undefined, numberOfMessagesToSkip: number = 0): string {
   // console.history is a global polyfill used in server rendering.
   const consoleHistory = customConsoleHistory ?? console.history;

node_package/src/clientStartup.ts

@@ -7,6 +7,7 @@ import type {
   RenderFunction,
   Root,
 } from './types';
+import type { Context } from './context';
 
 import createReactOutput from './createReactOutput';
 import { isServerRenderHash } from './isServerRenderResult';
@@ -22,12 +23,11 @@ declare global {
     roots: Root[];
   }
 
-  namespace NodeJS {
-    interface Global {
-      ReactOnRails: ReactOnRailsType;
-      roots: Root[];
-    }
+  namespace globalThis {
+    var ReactOnRails: ReactOnRailsType;
+    var roots: Root[];
   }
+
   namespace Turbolinks {
     interface TurbolinksStatic {
       controller?: unknown;
@@ -39,8 +39,6 @@ declare const ReactOnRails: ReactOnRailsType;
 
 const REACT_ON_RAILS_STORE_ATTRIBUTE = 'data-js-react-on-rails-store';
 
-type Context = Window | NodeJS.Global;
-
 function findContext(): Context {
   if (typeof window.ReactOnRails !== 'undefined') {
     return window;

node_package/src/context.ts

@@ -1,8 +1,9 @@
+export type Context = Window | typeof globalThis;
+
 /**
  * Get the context, be it window or global
- * @returns {boolean|Window|*|context}
  */
-export default function context(this: void): Window | NodeJS.Global | void {
+export default function context(this: void): Context | void {
   return ((typeof window !== 'undefined') && window) ||
     ((typeof global !== 'undefined') && global) ||
     this;

node_package/src/reactHydrateOrRender.ts

@@ -23,11 +23,11 @@ if (supportsRootApi) {
   }
 }
 
-export const reactHydrate: HydrateOrRenderType = supportsRootApi ?
+const reactHydrate: HydrateOrRenderType = supportsRootApi ?
   reactDomClient.hydrateRoot :
   (domNode, reactElement) => ReactDOM.hydrate(reactElement, domNode);
 
-export function reactRender(domNode: Element, reactElement: ReactElement): RenderReturnType {
+function reactRender(domNode: Element, reactElement: ReactElement): RenderReturnType {
   if (supportsRootApi) {
     const root = reactDomClient.createRoot(domNode);
     root.render(reactElement);

package.json

@@ -20,6 +20,7 @@
     "@babel/preset-react": "^7.18.6",
     "@babel/types": "^7.20.7",
     "@types/jest": "^29.5.14",
+    "@types/node": "^20.17.16",
     "@types/react": "^18.3.18",
     "@types/react-dom": "^18.3.5",
     "@types/turbolinks": "^5.2.2",
@@ -38,6 +39,7 @@
     "jest": "^29.7.0",
     "jest-environment-jsdom": "^29.7.0",
     "jsdom": "^22.1.0",
+    "knip": "^5.43.1",
     "nps": "^5.9.3",
     "prettier": "^2.8.8",
     "prettier-eslint-cli": "^5.0.0",
@@ -73,7 +75,8 @@
     "type-check": "yarn run tsc --noEmit --noErrorTruncation",
     "release:patch": "node_package/scripts/release patch",
     "release:minor": "node_package/scripts/release minor",
-    "release:major": "node_package/scripts/release major"
+    "release:major": "node_package/scripts/release major",
+    "knip": "knip"
   },
   "repository": {
     "type": "git",

script/convert

@@ -15,6 +15,9 @@ File.rename(old_config, new_config)
 
 gsub_file_content("../Gemfile.development_dependencies", 'gem "shakapacker", "8.0.0"', 'gem "shakapacker", "6.6.0"')
 
+# Knip doesn't work on the oldest supported Node version and isn't needed there anyway
+gsub_file_content("../package.json", /"knip": "[^"]*",/, "")
+
 gsub_file_content("../spec/dummy/package.json", '"shakapacker": "8.0.0",', '"shakapacker": "6.6.0",')
 
 gsub_file_content("../spec/dummy/config/webpack/commonWebpackConfig.js", /generateWebpackConfig(\(\))?/,