Use strict TypeScript-ESLint config

Author: alexeyr

eslint.config.ts

@@ -140,7 +140,7 @@ const config = tsEslint.config([
   {
     files: ['**/*.ts', '**/*.tsx'],
 
-    extends: tsEslint.configs.recommendedTypeChecked,
+    extends: tsEslint.configs.strictTypeChecked,
 
     languageOptions: {
       parserOptions: {
@@ -156,6 +156,12 @@ const config = tsEslint.config([
     rules: {
       '@typescript-eslint/no-namespace': 'off',
       '@typescript-eslint/no-shadow': 'error',
+      '@typescript-eslint/no-confusing-void-expression': [
+        'error',
+        {
+          ignoreArrowShorthand: true,
+        },
+      ],
       // Too many false positives
       '@typescript-eslint/no-unnecessary-condition': 'off',
       '@typescript-eslint/no-unused-vars': [

node_package/src/ClientSideRenderer.ts

@@ -1,5 +1,5 @@
 /* eslint-disable max-classes-per-file */
-/* eslint-disable react/no-deprecated -- while we need to support React 16 */
+/* eslint-disable react/no-deprecated,@typescript-eslint/no-deprecated -- while we need to support React 16 */
 
 import * as ReactDOM from 'react-dom';
 import type { ReactElement } from 'react';
@@ -163,8 +163,8 @@ You should return a React.Component always for the client side entry point.`);
   }
 
   waitUntilRendered(): Promise<void> {
-    if (this.state === 'rendering') {
-      return this.renderPromise!;
+    if (this.state === 'rendering' && this.renderPromise) {
+      return this.renderPromise;
     }
     return Promise.resolve();
   }
@@ -207,8 +207,8 @@ class StoreRenderer {
   }
 
   waitUntilHydrated(): Promise<void> {
-    if (this.state === 'hydrating') {
-      return this.hydratePromise!;
+    if (this.state === 'hydrating' && this.hydratePromise) {
+      return this.hydratePromise;
     }
     return Promise.resolve();
   }

node_package/src/ReactOnRails.client.ts

@@ -203,11 +203,10 @@ ctx.ReactOnRails = {
 
   /**
    * Allows saving the store populated by Rails form props. Used internally by ReactOnRails.
-   * @param name
    * @returns Redux Store, possibly hydrated
    */
   setStore(name: string, store: Store): void {
-    return StoreRegistry.setStore(name, store);
+    StoreRegistry.setStore(name, store);
   },
 
   /**

node_package/src/ReactOnRailsRSC.ts

@@ -46,7 +46,7 @@ const streamRenderRSCComponent = (reactElement: ReactElement, options: RSCRender
       });
       pipeToTransform(rscStream);
     })
-    .catch((e) => {
+    .catch((e: unknown) => {
       const error = convertToError(e);
       renderState.hasErrors = true;
       renderState.error = error;

node_package/src/clientStartup.ts

@@ -11,7 +11,9 @@ import { debugTurbolinks } from './turbolinksUtils';
 
 export async function reactOnRailsPageLoaded() {
   debugTurbolinks('reactOnRailsPageLoaded');
-  await Promise.all([hydrateAllStores(), renderOrHydrateAllComponents()]);
+  const promise = hydrateAllStores();
+  renderOrHydrateAllComponents();
+  await promise;
 }
 
 function reactOnRailsPageUnloaded(): void {

node_package/src/context.ts

@@ -18,6 +18,7 @@ export type Context = Window | typeof globalThis;
 /**
  * Get the context, be it window or global
  */
+// eslint-disable-next-line @typescript-eslint/no-invalid-void-type
 export default function context(this: void): Context | void {
   return (typeof window !== 'undefined' && window) || (typeof global !== 'undefined' && global) || this;
 }

node_package/src/loadReactClientManifest.ts

@@ -9,15 +9,17 @@ export default async function loadReactClientManifest(reactClientManifestFileNam
   // Renderer copies assets to the same place as the server-bundle.js and rsc-bundle.js.
   // Thus, the __dirname of this code is where we can find the manifest file.
   const manifestPath = path.resolve(__dirname, reactClientManifestFileName);
-  if (!loadedReactClientManifests.has(manifestPath)) {
+  const loadedReactClientManifest = loadedReactClientManifests.get(manifestPath);
+  if (!loadedReactClientManifest) {
     // TODO: convert to async
     try {
       const manifest = JSON.parse(await fs.readFile(manifestPath, 'utf8')) as ClientManifest;
       loadedReactClientManifests.set(manifestPath, manifest);
+      return manifest;
     } catch (error) {
       throw new Error(`Failed to load React client manifest from ${manifestPath}: ${error}`);
     }
   }
 
-  return loadedReactClientManifests.get(manifestPath)!;
+  return loadedReactClientManifest;
 }

node_package/src/reactHydrateOrRender.ts

@@ -22,22 +22,24 @@ if (supportsRootApi) {
   }
 }
 
-/* eslint-disable react/no-deprecated -- while we need to support React 16 */
+/* eslint-disable react/no-deprecated,@typescript-eslint/no-deprecated,@typescript-eslint/no-non-null-assertion --
+ * while we need to support React 16
+ */
 const reactHydrate: HydrateOrRenderType = supportsRootApi
-  ? reactDomClient.hydrateRoot
+  ? reactDomClient!.hydrateRoot
   : (domNode, reactElement) => ReactDOM.hydrate(reactElement, domNode);
 
 function reactRender(domNode: Element, reactElement: ReactElement): RenderReturnType {
   if (supportsRootApi) {
-    const root = reactDomClient.createRoot(domNode);
+    const root = reactDomClient!.createRoot(domNode);
     root.render(reactElement);
     return root;
   }
 
   // eslint-disable-next-line react/no-render-return-value
   return ReactDOM.render(reactElement, domNode);
 }
-/* eslint-enable react/no-deprecated */
+/* eslint-enable react/no-deprecated,@typescript-eslint/no-deprecated,@typescript-eslint/no-non-null-assertion */
 
 export default function reactHydrateOrRender(
   domNode: Element,

node_package/src/types/index.ts

@@ -166,6 +166,7 @@ export interface Root {
   unmount(): void;
 }
 
+// eslint-disable-next-line @typescript-eslint/no-invalid-void-type -- inherited from React 16/17, can't avoid here
 export type RenderReturnType = void | Element | Component | Root;
 
 export interface ReactOnRails {