Made typescript/strict-boolean-expressions even stricter

kaisalmen · kaisalmen · commit 3be1ff7ffdaf · 2026-03-05T15:02:11.000+01:00
diff --git a/.oxlintrc.json b/.oxlintrc.json
@@ -98,7 +98,14 @@
     "typescript/prefer-nullish-coalescing": "error",
     // currently in oxlint's nursery (=under development)
     "typescript/prefer-optional-chain": "error",
-    "typescript/strict-boolean-expressions": "error",
+    "typescript/strict-boolean-expressions": [
+      "error",
+      {
+        "allowString": false,
+        "allowNumber": false,
+        "allowNullableObject": false
+      }
+    ],
     "typescript/triple-slash-reference": "error",
     // all import related rules
     "import/no-duplicates": "error",
diff --git a/packages/client/src/common/utils.ts b/packages/client/src/common/utils.ts
@@ -7,7 +7,7 @@ import type { WebSocketUrlParams, WebSocketUrlString } from './commonTypes.js';
 
 export const createUrl = (config: WebSocketUrlParams | WebSocketUrlString) => {
     let buildUrl = '';
-    if ((config as WebSocketUrlString).url) {
+    if (Object.hasOwn(config, 'url')) {
         const options = config as WebSocketUrlString;
         if (!options.url.startsWith('ws://') && !options.url.startsWith('wss://')) {
             throw new Error(`This is not a proper websocket url: ${options.url}`);
@@ -25,7 +25,7 @@ export const createUrl = (config: WebSocketUrlParams | WebSocketUrlString) => {
         if (options.path !== undefined) {
             buildUrl += `/${options.path}`;
         }
-        if (options.extraParams) {
+        if (options.extraParams !== undefined) {
             const url = new URL(buildUrl);
 
             for (const [key, value] of Object.entries(options.extraParams)) {
diff --git a/packages/client/src/editorApp/editorApp.ts b/packages/client/src/editorApp/editorApp.ts
@@ -138,7 +138,7 @@ export class EditorApp {
             }
 
             const languageDef = this.config.languageDef;
-            if (languageDef) {
+            if (languageDef !== undefined) {
                 // register own language first
                 monaco.languages.register(languageDef.languageExtensionConfig);
 
@@ -151,11 +151,11 @@ export class EditorApp {
                 }
 
                 // apply monarch definitions
-                if (languageDef.monarchLanguage) {
+                if (languageDef.monarchLanguage !== undefined) {
                     monaco.languages.setMonarchTokensProvider(languageDef.languageExtensionConfig.id, languageDef.monarchLanguage);
                 }
 
-                if (languageDef.theme) {
+                if (languageDef.theme !== undefined) {
                     monaco.editor.defineTheme(languageDef.theme.name, languageDef.theme.data);
                     monaco.editor.setTheme(languageDef.theme.name);
                 }
@@ -343,11 +343,11 @@ export class EditorApp {
             disposingResolve = resolve;
         });
 
-        if (this.editor) {
+        if (this.editor !== undefined) {
             this.editor.dispose();
             this.editor = undefined;
         }
-        if (this.diffEditor) {
+        if (this.diffEditor !== undefined) {
             this.diffEditor.dispose();
             this.diffEditor = undefined;
         }
diff --git a/packages/client/src/vscode/apiWrapper.ts b/packages/client/src/vscode/apiWrapper.ts
@@ -261,7 +261,7 @@ export class MonacoVscodeApiWrapper {
         }
 
         const extensions = this.apiConfig.extensions;
-        if (this.apiConfig.extensions) {
+        if (this.apiConfig.extensions !== undefined && this.apiConfig.extensions.length > 0) {
             const allPromises: Array<Promise<void>> = [];
             const extensionIds: string[] = [];
             getBuiltinExtensions().forEach((ext) => {
@@ -281,7 +281,7 @@ export class MonacoVscodeApiWrapper {
             const manifest = extensionConfig.config as IExtensionManifest;
             const extRegResult = registerExtension(manifest, ExtensionHostKind.LocalProcess);
             this.extensionRegisterResults.set(manifest.name, extRegResult);
-            if (extensionConfig.filesOrContents && Object.hasOwn(extRegResult, 'registerFileUrl')) {
+            if (extensionConfig.filesOrContents !== undefined && Object.hasOwn(extRegResult, 'registerFileUrl')) {
                 for (const entry of extensionConfig.filesOrContents) {
                     this.disposableStore.add(extRegResult.registerFileUrl(entry[0], encodeStringOrUrlToDataUrl(entry[1])));
                 }
diff --git a/packages/client/src/vscode/locales.ts b/packages/client/src/vscode/locales.ts
@@ -120,7 +120,7 @@ export const locales = Object.keys(localeLoader);
 export const initLocaleLoader = async (locale = new URLSearchParams(window.location.search).get('locale'), logger?: ILogger) => {
     if (locale !== null) {
         const loader = localeLoader[locale];
-        if (loader) {
+        if (loader !== undefined) {
             await loader();
         } else {
             logger?.error(`Unknown locale ${locale}`);
diff --git a/packages/client/src/wrapper/lcwrapper.ts b/packages/client/src/wrapper/lcwrapper.ts
@@ -112,7 +112,7 @@ export class LanguageClientWrapper {
     }
 
     protected async initMessageTransportWorker(lccOptions: WorkerConfigOptionsDirect | WorkerConfigOptionsParams, resolve: () => void, reject: (reason?: unknown) => void) {
-        if (!this.worker) {
+        if (this.worker === undefined) {
             if (lccOptions.$type === 'WorkerConfig') {
                 const workerConfig = lccOptions as WorkerConfigOptionsParams;
                 this.worker = new Worker(workerConfig.url.href, {
diff --git a/packages/examples/src/clangd/worker/clangd-server.ts b/packages/examples/src/clangd/worker/clangd-server.ts
@@ -109,7 +109,7 @@ export class ClangdInteractionWorker implements ComRouter {
         while (!loadingComplete) {
             const { done, value } = await wasmReader.read();
             loadingComplete = done;
-            if (value) {
+            if (value !== undefined) {
                 chunks.push(value);
             }
         }
@@ -276,7 +276,7 @@ export class ClangdInteractionWorker implements ComRouter {
      * @param readOrWrite Whether to read or write the filesystem
      */
     private syncFS(readOrWrite: boolean) {
-        if (!this.emscriptenFS) throw new Error('Emscripten FS is not available! Aborting ...');
+        if (this.emscriptenFS === undefined) throw new Error('Emscripten FS is not available! Aborting ...');
 
         this.emscriptenFS.syncfs(readOrWrite, (err) => {
             if (err !== null) {
@@ -287,7 +287,7 @@ export class ClangdInteractionWorker implements ComRouter {
     }
 
     private async updateWorkerFilesystem(requiredResurces: RequiredResources) {
-        if (!this.emscriptenFS) throw new Error('Emscripten FS is not available! Aborting ...');
+        if (this.emscriptenFS === undefined) throw new Error('Emscripten FS is not available! Aborting ...');
 
         const t0 = performance.now();
         console.log('Updating Worker FS');
@@ -310,7 +310,7 @@ export class ClangdInteractionWorker implements ComRouter {
      * Loads workspace files separately or the compressed workspace from a zip archive
      */
     private async loadWorkspaceFiles() {
-        if (!this.emscriptenFS) throw new Error('Emscripten FS is not available! Aborting ...');
+        if (this.emscriptenFS === undefined) throw new Error('Emscripten FS is not available! Aborting ...');
 
         // setup & prepare the filesystem
         this.emscriptenFS.mkdir(WORKSPACE_PATH);
@@ -365,7 +365,7 @@ export class ClangdInteractionWorker implements ComRouter {
     }
 
     private async processInputFiles(files: Record<string, () => Promise<unknown>>, dirReplacer: string) {
-        if (!this.emscriptenFS) throw new Error('Emscripten FS is not available! Aborting ...');
+        if (this.emscriptenFS === undefined) throw new Error('Emscripten FS is not available! Aborting ...');
 
         const dirsToCreate = new Set<string>();
         const filesToUse: Record<string, () => Promise<unknown>> = {};
@@ -428,8 +428,8 @@ export class ClangdInteractionWorker implements ComRouter {
     }
 
     private async updateRemoteFilesystem() {
-        if (!this.emscriptenFS) throw new Error('Emscripten FS is not available! Aborting ...');
-        if (!this.fsMessagePort) throw new Error('MessagePort is not available! Aborting ...');
+        if (this.emscriptenFS === undefined) throw new Error('Emscripten FS is not available! Aborting ...');
+        if (this.fsMessagePort === undefined) throw new Error('MessagePort is not available! Aborting ...');
 
         const t0 = performance.now();
 
diff --git a/packages/examples/src/clangd/worker/json_stream.ts b/packages/examples/src/clangd/worker/json_stream.ts
@@ -33,7 +33,7 @@ export class JsonStream {
         }
         this.#rawText.push(charCode);
         if (this.#inString) {
-            if (this.#inEscape) {
+            if (this.#inEscape > 0) {
                 if (charCode === 75) {
                     // \uxxxx
                     this.#inEscape += 4;
diff --git a/packages/examples/src/common/node/server-commons.ts b/packages/examples/src/common/node/server-commons.ts
@@ -77,7 +77,7 @@ export const upgradeWsServer = (runconfig: LanguageServerRunConfig,
             config.wss.handleUpgrade(request, socket, head, webSocket => {
                 const socket: IWebSocket = {
                     send: content => webSocket.send(content, error => {
-                        if (error) {
+                        if (error !== undefined) {
                             throw error;
                         }
                     }),
diff --git a/packages/examples/src/json/server/json-server.ts b/packages/examples/src/json/server/json-server.ts
@@ -105,15 +105,15 @@ export class JsonServer {
 
     protected getFoldingRanges(params: FoldingRangeParams): FoldingRange[] {
         const document = this.documents.get(params.textDocument.uri);
-        if (!document) {
+        if (document === undefined) {
             return [];
         }
         return this.jsonService.getFoldingRanges(document);
     }
 
     protected findDocumentColors(params: DocumentColorParams): Thenable<ColorInformation[]> {
         const document = this.documents.get(params.textDocument.uri);
-        if (!document) {
+        if (document === undefined) {
             return Promise.resolve([]);
         }
         const jsonDocument = this.getJSONDocument(document);
@@ -122,7 +122,7 @@ export class JsonServer {
 
     protected getColorPresentations(params: ColorPresentationParams): ColorPresentation[] {
         const document = this.documents.get(params.textDocument.uri);
-        if (!document) {
+        if (document === undefined) {
             return [];
         }
         const jsonDocument = this.getJSONDocument(document);
@@ -131,7 +131,7 @@ export class JsonServer {
 
     protected codeAction(params: CodeActionParams): Command[] {
         const document = this.documents.get(params.textDocument.uri);
-        if (!document) {
+        if (document === undefined) {
             return [];
         }
         return [{
@@ -147,12 +147,12 @@ export class JsonServer {
 
     protected format(params: DocumentRangeFormattingParams): TextEdit[] {
         const document = this.documents.get(params.textDocument.uri);
-        return document ? this.jsonService.format(document, params.range, params.options) : [];
+        return document === undefined ? [] : this.jsonService.format(document, params.range, params.options);
     }
 
     protected findDocumentSymbols(params: DocumentSymbolParams): SymbolInformation[] {
         const document = this.documents.get(params.textDocument.uri);
-        if (!document) {
+        if (document === undefined) {
             return [];
         }
         const jsonDocument = this.getJSONDocument(document);
@@ -161,10 +161,10 @@ export class JsonServer {
 
     // oxlint-disable-next-line @typescript-eslint/no-explicit-any
     protected async executeCommand(params: ExecuteCommandParams): Promise<any> {
-        if (params.command === 'json.documentUpper' && params.arguments) {
+        if (params.command === 'json.documentUpper' && params.arguments !== undefined) {
             const versionedTextDocumentIdentifier = params.arguments[0];
             const document = this.documents.get(versionedTextDocumentIdentifier.uri);
-            if (document) {
+            if (document !== undefined) {
                 await this.connection.workspace.applyEdit({
                     documentChanges: [{
                         textDocument: versionedTextDocumentIdentifier,
@@ -183,7 +183,7 @@ export class JsonServer {
 
     protected hover(params: TextDocumentPositionParams): Thenable<Hover | null> {
         const document = this.documents.get(params.textDocument.uri);
-        if (!document) {
+        if (document === undefined) {
             return Promise.resolve(null);
         }
         const jsonDocument = this.getJSONDocument(document);
@@ -227,7 +227,7 @@ export class JsonServer {
 
     protected completion(params: TextDocumentPositionParams): Thenable<CompletionList | null> {
         const document = this.documents.get(params.textDocument.uri);
-        if (!document) {
+        if (document === undefined) {
             return Promise.resolve(null);
         }
         const jsonDocument = this.getJSONDocument(document);
diff --git a/packages/examples/src/langium/statemachine/ls/statemachine-module.ts b/packages/examples/src/langium/statemachine/ls/statemachine-module.ts
@@ -64,7 +64,7 @@ export async function createStatemachineServices(context: DefaultSharedModuleCon
     );
     shared.ServiceRegistry.register(statemachine);
     registerValidationChecks(statemachine);
-    if (!context.connection) {
+    if (context.connection === undefined) {
         // We don't run inside a language server
         // Therefore, initialize the configuration provider instantly
         await shared.workspace.ConfigurationProvider.initialized({});
diff --git a/packages/examples/src/langium/statemachine/ls/statemachine-validator.ts b/packages/examples/src/langium/statemachine/ls/statemachine-validator.ts
@@ -25,7 +25,7 @@ export class StatemachineValidator {
      * @param accept the acceptor to report errors
      */
     checkStateNameStartsWithCapital(state: State, accept: ValidationAcceptor): void {
-        if (state.name) {
+        if (state.name.length > 0) {
             const firstChar = state.name.substring(0, 1);
             if (firstChar.toUpperCase() !== firstChar) {
                 accept('warning', 'State name should start with a capital letter.', { node: state, property: 'name' });
diff --git a/packages/wrapper-react/src/index.tsx b/packages/wrapper-react/src/index.tsx
@@ -158,7 +158,7 @@ export const MonacoEditorReactComp: React.FC<MonacoEditorProps> = (props) => {
 
     const performErrorHandling = (error: Error) => {
         debugLogging(`ERROR: ${error.message}`);
-        if (onError) {
+        if (onError !== undefined) {
             onError(error);
         } else {
             debugLogging(`INTERCEPTED Error: ${error}. Stopping queue...`);
@@ -205,7 +205,9 @@ export const MonacoEditorReactComp: React.FC<MonacoEditorProps> = (props) => {
         try {
             // it is possible to run without an editorApp, when the ViewsService or WorkbenchService
             if (haveEditorService()) {
-                if (!htmlContainer?.parentElement) {
+
+                // oxlint-disable-next-line typescript/prefer-optional-chain
+                if (htmlContainer === null || htmlContainer.parentElement === null) {
                     debugLogging('INIT EDITOR: Unable to create editor. HTML container or the parent is missing.');
                 } else {
                     if (editorAppRef.current === undefined && !launchingRef.current) {
@@ -251,7 +253,7 @@ export const MonacoEditorReactComp: React.FC<MonacoEditorProps> = (props) => {
 
     const updateEditorModel = async () => {
         try {
-            if (!launchingRef.current && editorAppRef.current) {
+            if (!launchingRef.current && editorAppRef.current !== undefined) {
                 await editorAppRef.current.updateCodeResources(editorAppConfigRef.current?.codeResources);
                 updateModelRelatedRefs();
                 onConfigProcessed?.({ modelUpdated: true, textUpdated: true, editorApp: editorAppRef.current });
@@ -293,7 +295,7 @@ export const MonacoEditorReactComp: React.FC<MonacoEditorProps> = (props) => {
         let textUpdated = false;
         try {
             debugLogging('CONFIG PROCESSED: Started');
-            if (!launchingRef.current && editorAppRef.current) {
+            if (!launchingRef.current && editorAppRef.current !== undefined) {
                 if (editorAppConfigRef.current?.codeResources !== undefined) {
                     const newModifiedCodeUri = editorAppConfigRef.current.codeResources.modified?.uri;
                     const newOriginalCodeUri = editorAppConfigRef.current.codeResources.original?.uri;

Original file line number	Diff line number	Diff line change
`@@ -138,7 +138,7 @@ export class EditorApp {`
`138`	`138`	`}`
`139`	`139`
`140`	`140`	`const languageDef = this.config.languageDef;`
`141`		`- if (languageDef) {`
	`141`	`+ if (languageDef !== undefined) {`
`142`	`142`	`// register own language first`
`143`	`143`	`monaco.languages.register(languageDef.languageExtensionConfig);`
`144`	`144`
`@@ -151,11 +151,11 @@ export class EditorApp {`
`151`	`151`	`}`
`152`	`152`
`153`	`153`	`// apply monarch definitions`
`154`		`- if (languageDef.monarchLanguage) {`
	`154`	`+ if (languageDef.monarchLanguage !== undefined) {`
`155`	`155`	`monaco.languages.setMonarchTokensProvider(languageDef.languageExtensionConfig.id, languageDef.monarchLanguage);`
`156`	`156`	`}`
`157`	`157`
`158`		`- if (languageDef.theme) {`
	`158`	`+ if (languageDef.theme !== undefined) {`
`159`	`159`	`monaco.editor.defineTheme(languageDef.theme.name, languageDef.theme.data);`
`160`	`160`	`monaco.editor.setTheme(languageDef.theme.name);`
`161`	`161`	`}`
`@@ -343,11 +343,11 @@ export class EditorApp {`
`343`	`343`	`disposingResolve = resolve;`
`344`	`344`	`});`
`345`	`345`
`346`		`- if (this.editor) {`
	`346`	`+ if (this.editor !== undefined) {`
`347`	`347`	`this.editor.dispose();`
`348`	`348`	`this.editor = undefined;`
`349`	`349`	`}`
`350`		`- if (this.diffEditor) {`
	`350`	`+ if (this.diffEditor !== undefined) {`
`351`	`351`	`this.diffEditor.dispose();`
`352`	`352`	`this.diffEditor = undefined;`
`353`	`353`	`}`
Original file line number	Diff line number	Diff line change
`@@ -112,7 +112,7 @@ export class LanguageClientWrapper {`
`112`	`112`	`}`
`113`	`113`
`114`	`114`	`protected async initMessageTransportWorker(lccOptions: WorkerConfigOptionsDirect \| WorkerConfigOptionsParams, resolve: () => void, reject: (reason?: unknown) => void) {`
`115`		`- if (!this.worker) {`
	`115`	`+ if (this.worker === undefined) {`
`116`	`116`	`if (lccOptions.$type === 'WorkerConfig') {`
`117`	`117`	`const workerConfig = lccOptions as WorkerConfigOptionsParams;`
`118`	`118`	`this.worker = new Worker(workerConfig.url.href, {`
Original file line number	Diff line number	Diff line change
`@@ -33,7 +33,7 @@ export class JsonStream {`
`33`	`33`	`}`
`34`	`34`	`this.#rawText.push(charCode);`
`35`	`35`	`if (this.#inString) {`
`36`		`- if (this.#inEscape) {`
	`36`	`+ if (this.#inEscape > 0) {`
`37`	`37`	`if (charCode === 75) {`
`38`	`38`	`// \uxxxx`
`39`	`39`	`this.#inEscape += 4;`
Original file line number	Diff line number	Diff line change
`@@ -77,7 +77,7 @@ export const upgradeWsServer = (runconfig: LanguageServerRunConfig,`
`77`	`77`	`config.wss.handleUpgrade(request, socket, head, webSocket => {`
`78`	`78`	`const socket: IWebSocket = {`
`79`	`79`	`send: content => webSocket.send(content, error => {`
`80`		`- if (error) {`
	`80`	`+ if (error !== undefined) {`
`81`	`81`	`throw error;`
`82`	`82`	`}`
`83`	`83`	`}),`