Enable linting with type information.

.eslintrc.cjs

@@ -3,12 +3,16 @@ module.exports = {
   env: { browser: true, es2020: true },
   extends: [
     "eslint:recommended",
-    "plugin:@typescript-eslint/recommended",
+    "plugin:@typescript-eslint/recommended-type-checked",
     "plugin:react-hooks/recommended",
     "prettier", // Comes last, to turn off rules from above that conflict with Prettier.
   ],
   ignorePatterns: ["dist", ".eslintrc.cjs"],
   parser: "@typescript-eslint/parser",
+  parserOptions: {
+    project: ["./tsconfig.json", "./tsconfig.node.json"],
+    tsconfigRootDir: __dirname,
+  },
   plugins: ["react-refresh"],
   rules: {
     "react-refresh/only-export-components": [

src/App.tsx

@@ -121,6 +121,8 @@ function useIndex(file: File | null): IndexState {
     };
 
     if (file) {
+      // TODO: Handle errors from this floating promise.
+      // eslint-disable-next-line @typescript-eslint/no-floating-promises
       buildIndex(file, debounceProgress(handleProgress)).then((index) => {
         if (!ignore) setIndexState({ status: "indexed", index });
       });
@@ -170,6 +172,8 @@ function useSearch(indexState: IndexState, query: string): SearchResult {
           }
         }
       };
+      // TODO: Handle errors from this floating promise.
+      // eslint-disable-next-line @typescript-eslint/no-floating-promises
       doSearch();
     }
     return () => {

src/ResourceMonitor.tsx

@@ -2,13 +2,21 @@ import * as React from "react";
 
 const MEASUREMENT_INTERVAL = 2000;
 
+// Inform TypeScript of the not-universally-supported performance.memory API.
+// https://www.typescriptlang.org/docs/handbook/namespaces.html#working-with-other-javascript-libraries.
+// Unclear why the linter is complaining about this.
+// eslint-disable-next-line @typescript-eslint/no-namespace
+declare namespace performance {
+  const memory: {
+    usedJSHeapSize: number;
+  };
+}
+
 export function ResourceMonitor(): JSX.Element {
   const [bytes, setBytes] = React.useState<number | null>(null);
   React.useEffect(() => {
     const interval = window.setInterval(() => {
-      // @ts-expect-error performance.memory is Chrome-only.
       if (performance.memory) {
-        // @ts-expect-error performance.memory is Chrome-only.
         setBytes(performance.memory.usedJSHeapSize);
       }
     }, MEASUREMENT_INTERVAL);

src/journalParsing/jsonRecordSplitter.ts

@@ -18,7 +18,7 @@ interface SplitLine {
 }
 
 export interface ParsedJSON {
-  parsedJSON: object;
+  parsedJSON: unknown;
   beginByteIndex: number;
   endByteIndex: number;
 }

src/journalParsing/parseNative.test.ts

@@ -232,7 +232,7 @@ test.each(testCases)(
       }
       expect(events).toStrictEqual(expectedEvents);
     } finally {
-      file.close();
+      await file.close();
     }
   },
 );

src/journalParsing/parseNative.ts

@@ -96,10 +96,7 @@ async function readNewline(bytes: AsyncIterator<number>): Promise<void> {
 
 async function readFieldName(
   bytes: AsyncIterable<number>,
-): Promise<
-  | "gracefulEOF"
-  | { fieldName: string; termination: typeof EQUALS | typeof NEWLINE }
-> {
+): Promise<"gracefulEOF" | { fieldName: string; termination: number }> {
   const bytesToDecode: number[] = [];
 
   for await (const byte of bytes) {

src/logAccess.ts

@@ -114,19 +114,20 @@ export async function buildIndex(
 
 function parseEntry(parsed: ParsedJSON): LogEntry {
   // TODO: We should probably validate this. The input file is untrusted.
-  const json = parsed.parsedJSON;
-  // @ts-expect-error JSON object is untyped.
-  const epochMicroseconds = parseInt(json["__REALTIME_TIMESTAMP"]);
+  const json = parsed.parsedJSON as {
+    __REALTIME_TIMESTAMP: string;
+    PRIORITY: string;
+    _SYSTEMD_UNIT: string;
+    SYSLOG_IDENTIFIER: string;
+    MESSAGE: string;
+  };
+  const epochMicroseconds = parseInt(json.__REALTIME_TIMESTAMP);
   return {
     timestamp: new Date(epochMicroseconds / 1000),
-    // @ts-expect-error JSON object is untyped.
-    priority: parseInt(json["PRIORITY"]),
-    // @ts-expect-error JSON object is untyped.
-    unit: json["_SYSTEMD_UNIT"], // TODO: Also support _SYSTEMD_USER_UNIT?
-    // @ts-expect-error JSON object is untyped.
-    syslogIdentifier: json["SYSLOG_IDENTIFIER"],
-    // @ts-expect-error JSON object is untyped.
-    message: json["MESSAGE"],
+    priority: parseInt(json.PRIORITY),
+    unit: json._SYSTEMD_UNIT, // TODO: Also support _SYSTEMD_USER_UNIT?
+    syslogIdentifier: json.SYSLOG_IDENTIFIER,
+    message: json.MESSAGE,
   };
 }