Fix good lints given by eslint-plugin-unicorn

.eslintrc.json

@@ -16,7 +16,7 @@
         "plugin:@typescript-eslint/stylistic"
     ],
     "plugins": [
-        "@typescript-eslint", "no-null", "eslint-plugin-local", "simple-import-sort"
+        "@typescript-eslint", "no-null", "eslint-plugin-local", "simple-import-sort", "unicorn"
     ],
     "ignorePatterns": [
         "**/node_modules/**",
@@ -123,6 +123,27 @@
         "local/no-keywords": "error",
         "local/jsdoc-format": "error",
 
+        // eslint-plugin-unicorn
+        "unicorn/prefer-includes": "error",
+        "unicorn/new-for-builtins": "error",
+        "unicorn/prefer-logical-operator-over-ternary": "error",
+        "unicorn/no-instanceof-array": "error",
+        "unicorn/prefer-optional-catch-binding": "error",
+        "unicorn/require-array-join-separator": "error",
+        "unicorn/throw-new-error": "error",
+        "unicorn/no-useless-spread": "error",
+        "unicorn/no-useless-fallback-in-spread": "error",
+        "unicorn/prefer-modern-math-apis": "error",
+        "unicorn/prefer-array-find": "error",
+        "unicorn/prefer-array-some": "error",
+        "unicorn/prefer-date-now": "error",
+        "unicorn/prefer-object-from-entries": "error",
+        "unicorn/no-new-buffer": "error",
+        "unicorn/prefer-set-has": "error",
+        // TODO(jakebailey): Require manual fixups
+        // "unicorn/prefer-string-slice": "error",
+        // "unicorn/prefer-string-trim-start-end": "error", // check perf vs helper
+
         // eslint-plugin-no-null
         "no-null/no-null": "error",
 

package.json

@@ -66,6 +66,7 @@
         "eslint-plugin-local": "^1.0.0",
         "eslint-plugin-no-null": "^1.0.2",
         "eslint-plugin-simple-import-sort": "^10.0.0",
+        "eslint-plugin-unicorn": "^48.0.1",
         "fast-xml-parser": "^4.0.11",
         "glob": "^8.1.0",
         "hereby": "^1.6.4",

scripts/browserIntegrationTest.mjs

@@ -11,7 +11,7 @@ try {
     // @ts-ignore-error
     playwright = await import("playwright");
 }
-catch (error) {
+catch {
     throw new Error("Playwright is expected to be installed manually before running this script");
 }
 

scripts/errorCheck.mjs

@@ -27,7 +27,7 @@ async function checkErrorBaselines() {
             let g;
             while (g = errRegex.exec(baseline)) {
                 const errCode = +g[1];
-                const msg = keys.filter(k => messages[k].code === errCode)[0];
+                const msg = keys.find(k => messages[k].code === errCode);
                 messages[msg].seen = true;
             }
         });

scripts/eslint/rules/no-keywords.cjs

@@ -22,7 +22,7 @@ module.exports = createRule({
     defaultOptions: [],
 
     create(context) {
-        const keywords = [
+        const keywords = new Set([
             "Undefined",
             "undefined",
             "Boolean",
@@ -32,10 +32,10 @@ module.exports = createRule({
             "Number",
             "number",
             "any",
-        ];
+        ]);
 
         /** @type {(name: string) => boolean} */
-        const isKeyword = name => keywords.includes(name);
+        const isKeyword = name => keywords.has(name);
 
         /** @type {(node: TSESTree.Identifier) => void} */
         const report = node => {

scripts/eslint/rules/only-arrow-functions.cjs

@@ -28,7 +28,7 @@ module.exports = createRule({
 
     create(context, [{ allowNamedFunctions, allowDeclarations }]) {
         /** @type {(node: TSESTree.FunctionDeclaration | TSESTree.FunctionExpression) => boolean} */
-        const isThisParameter = node => !!node.params.length && !!node.params.find(param => param.type === AST_NODE_TYPES.Identifier && param.name === "this");
+        const isThisParameter = node => node.params.some(param => param.type === AST_NODE_TYPES.Identifier && param.name === "this");
 
         /** @type {(node: TSESTree.Node) => boolean} */
         const isMethodType = node => {

scripts/failed-tests.cjs

@@ -45,7 +45,7 @@ class FailedTestsReporter extends Mocha.reporters.Base {
                 try {
                     reporter = require(reporterOptions.reporter);
                 }
-                catch (_) {
+                catch {
                     reporter = require(path.resolve(process.cwd(), reporterOptions.reporter));
                 }
             }

scripts/find-unused-diganostic-messages.mjs

@@ -24,7 +24,7 @@ startOfDiags.split(EOL).forEach(line => {
         execSync(`grep -rnw 'src' -e 'Diagnostics.${diagName}'`).toString();
         process.stdout.write(".");
     }
-    catch (error) {
+    catch {
         missingNames.push(diagName);
         process.stdout.write("x");
     }

scripts/update-experimental-branches.mjs

@@ -26,7 +26,7 @@ async function main() {
         owner: "Microsoft",
         repo: "TypeScript",
     })).data.filter(i => !!i.pull_request).map(i => i.number);
-    if (triggeredPR && !prnums.some(n => n === +triggeredPR)) {
+    if (triggeredPR && !prnums.includes(+triggeredPR)) {
         return; // Only have work to do for enlisted PRs
     }
     console.log(`Performing experimental branch updating and merging for pull requests ${prnums.join(", ")}`);

src/compiler/builder.ts

@@ -1217,7 +1217,7 @@ function getBuildInfo(state: BuilderProgramState, bundle: BundleBuildInfo | unde
 
     function toFileIdListId(set: ReadonlySet<Path>): ProgramBuildInfoFileIdListId {
         const fileIds = arrayFrom(set.keys(), toFileId).sort(compareValues);
-        const key = fileIds.join();
+        const key = fileIds.join(",");
         let fileIdListId = fileNamesToFileIdListId?.get(key);
         if (fileIdListId === undefined) {
             (fileIdsList ||= []).push(fileIds);
@@ -1783,7 +1783,7 @@ export function toBuilderFileEmit(value: ProgramBuilderInfoFilePendingEmit, full
 
 /** @internal */
 export function toProgramEmitPending(value: ProgramBuildInfoBundlePendingEmit, options: CompilerOptions | undefined): BuilderFileEmit | undefined {
-    return !value ? getBuilderFileEmit(options || {}) : value;
+    return value || getBuilderFileEmit(options || {});
 }
 
 /** @internal */

src/compiler/checker.ts

@@ -11722,6 +11722,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             // up recursively calling getTypeOfAlias, causing a stack overflow.
             links.type = exportSymbol?.declarations && isDuplicatedCommonJSExport(exportSymbol.declarations) && symbol.declarations!.length ? getFlowTypeFromCommonJSExport(exportSymbol)
                 : isDuplicatedCommonJSExport(symbol.declarations) ? autoType
+                // eslint-disable-next-line unicorn/prefer-logical-operator-over-ternary
                 : declaredType ? declaredType
                 : getSymbolFlags(targetSymbol) & SymbolFlags.Value ? getTypeOfSymbol(targetSymbol)
                 : errorType;
@@ -14364,7 +14365,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             }
             const writeType = getWriteTypeOfSymbol(prop);
             if (writeTypes || writeType !== type) {
-                writeTypes = append(!writeTypes ? propTypes.slice() : writeTypes, writeType);
+                writeTypes = append(writeTypes ?? propTypes.slice(), writeType);
             }
             else if (type !== firstType) {
                 checkFlags |= CheckFlags.HasNonUniformType;
@@ -14641,6 +14642,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         // the intersected key type, we just use unknownType for the key type as nothing actually depends on the
         // keyType property of the returned IndexInfo.
         return applicableInfos ? createIndexInfo(unknownType, getIntersectionType(map(applicableInfos, info => info.type)), reduceLeft(applicableInfos, (isReadonly, info) => isReadonly && info.isReadonly, /*initial*/ true)) :
+            // eslint-disable-next-line unicorn/prefer-logical-operator-over-ternary
             applicableInfo ? applicableInfo :
             stringIndexInfo && isApplicableIndexType(keyType, stringType) ? stringIndexInfo :
             undefined;
@@ -16369,7 +16371,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             return readonly ? globalReadonlyArrayType : globalArrayType;
         }
         const memberIds = mapDefined(namedMemberDeclarations, node => node ? getNodeId(node) : undefined);
-        const key = map(elementFlags, f => f & ElementFlags.Required ? "#" : f & ElementFlags.Optional ? "?" : f & ElementFlags.Rest ? "." : "*").join() +
+        const key = map(elementFlags, f => f & ElementFlags.Required ? "#" : f & ElementFlags.Optional ? "?" : f & ElementFlags.Rest ? "." : "*").join(",") +
             (readonly ? "R" : "") +
             (memberIds.length ? "," + memberIds.join(",") : "");
         let type = tupleTypes.get(key);
@@ -46412,7 +46414,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 else {
                     const copy = createSymbol(SymbolFlags.Signature, InternalSymbolName.Index);
                     copy.declarations = mapDefined(infos, i => i.declaration);
-                    copy.parent = type.aliasSymbol ? type.aliasSymbol : type.symbol ? type.symbol : getSymbolAtLocation(copy.declarations[0].parent);
+                    copy.parent = type.aliasSymbol ?? type.symbol ?? getSymbolAtLocation(copy.declarations[0].parent);
                     symbolLinks.filteredIndexSymbolCache.set(nodeListId, copy);
                     return copy;
                 }
@@ -49858,6 +49860,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
     function getEffectivePropertyNameForPropertyNameNode(node: PropertyName) {
         const name = getPropertyNameForPropertyNameNode(node);
+        // eslint-disable-next-line unicorn/prefer-logical-operator-over-ternary
         return name ? name :
             isComputedPropertyName(node) ? tryGetNameFromType(getTypeOfExpression(node.expression)) : undefined;
     }

src/compiler/commandLineParser.ts

@@ -2481,7 +2481,7 @@ export function convertToTSConfig(configParseResult: ParsedCommandLine, configFi
             version: undefined,
         },
         watchOptions: watchOptionMap && optionMapToObject(watchOptionMap),
-        references: map(configParseResult.projectReferences, r => ({ ...r, path: r.originalPath ? r.originalPath : "", originalPath: undefined })),
+        references: map(configParseResult.projectReferences, r => ({ ...r, path: r.originalPath || "", originalPath: undefined })),
         files: length(files) ? files : undefined,
         ...(configParseResult.options.configFile?.configFileSpecs ? {
             include: filterSameAsDefaultInclude(configParseResult.options.configFile.configFileSpecs.validatedIncludeSpecs),
@@ -2493,10 +2493,8 @@ export function convertToTSConfig(configParseResult: ParsedCommandLine, configFi
 }
 
 /** @internal */
-export function optionMapToObject(optionMap: Map<string, CompilerOptionsValue>): object {
-    return {
-        ...arrayFrom(optionMap.entries()).reduce((prev, cur) => ({ ...prev, [cur[0]]: cur[1] }), {}),
-    };
+export function optionMapToObject(optionMap: Map<string, CompilerOptionsValue>) {
+    return Object.fromEntries(optionMap.entries());
 }
 
 function filterSameAsDefaultInclude(specs: readonly string[] | undefined) {
@@ -2615,7 +2613,7 @@ export function getCompilerOptionsDiffValue(options: CompilerOptions, newLine: s
     return getOverwrittenDefaultOptions();
 
     function makePadding(paddingLength: number): string {
-        return Array(paddingLength + 1).join(" ");
+        return new Array(paddingLength + 1).join(" ");
     }
 
     function getOverwrittenDefaultOptions() {
@@ -2659,7 +2657,7 @@ export function generateTSConfig(options: CompilerOptions, fileNames: readonly s
     return writeConfigurations();
 
     function makePadding(paddingLength: number): string {
-        return Array(paddingLength + 1).join(" ");
+        return new Array(paddingLength + 1).join(" ");
     }
 
     function isAllowedOptionForOutput({ category, name, isCommandLineOnly }: CommandLineOption): boolean {

src/compiler/debug.ts

@@ -1048,7 +1048,7 @@ m2: ${(this.mapper2 as unknown as DebugTypeMapper).__debugToString().split("\n")
         }
 
         function computeColumnWidths(height: number) {
-            const columns: number[] = fill(Array(height), 0);
+            const columns: number[] = fill(new Array(height), 0);
             for (const node of nodes) {
                 columns[node.level] = Math.max(columns[node.level], node.text.length);
             }
@@ -1121,9 +1121,9 @@ m2: ${(this.mapper2 as unknown as DebugTypeMapper).__debugToString().split("\n")
         function renderGraph() {
             const columnCount = columnWidths.length;
             const laneCount = nodes.reduce((x, n) => Math.max(x, n.lane), 0) + 1;
-            const lanes: string[] = fill(Array(laneCount), "");
-            const grid: (FlowGraphNode | undefined)[][] = columnWidths.map(() => Array(laneCount));
-            const connectors: Connection[][] = columnWidths.map(() => fill(Array(laneCount), 0));
+            const lanes: string[] = fill(new Array(laneCount), "");
+            const grid: (FlowGraphNode | undefined)[][] = columnWidths.map(() => new Array(laneCount));
+            const connectors: Connection[][] = columnWidths.map(() => fill(new Array(laneCount), 0));
 
             // build connectors
             for (const node of nodes) {

src/compiler/moduleNameResolver.ts

@@ -2241,6 +2241,7 @@ function loadEntrypointsFromExportMap(
                 });
             }
             else {
+                // eslint-disable-next-line unicorn/prefer-set-has
                 const partsAfterFirst = getPathComponents(target).slice(2);
                 if (partsAfterFirst.includes("..") || partsAfterFirst.includes(".") || partsAfterFirst.includes("node_modules")) {
                     return false;
@@ -2675,6 +2676,7 @@ function getLoadModuleFromTargetImportOrExport(extensions: Extensions, state: Mo
                 return toSearchResult(/*value*/ undefined);
             }
             const parts = pathIsRelative(target) ? getPathComponents(target).slice(1) : getPathComponents(target);
+            // eslint-disable-next-line unicorn/prefer-set-has
             const partsAfterFirst = parts.slice(1);
             if (partsAfterFirst.includes("..") || partsAfterFirst.includes(".") || partsAfterFirst.includes("node_modules")) {
                 if (state.traceEnabled) {

src/compiler/parser.ts

@@ -10437,7 +10437,7 @@ export function processCommentPragmas(context: PragmaContext, sourceText: string
     for (const pragma of pragmas) {
         if (context.pragmas.has(pragma.name)) {
             const currentValue = context.pragmas.get(pragma.name);
-            if (currentValue instanceof Array) {
+            if (Array.isArray(currentValue)) {
                 currentValue.push(pragma.args);
             }
             else {
@@ -10497,7 +10497,7 @@ export function processPragmasIntoFields(context: PragmaContext, reportDiagnosti
                 break;
             }
             case "amd-module": {
-                if (entryOrList instanceof Array) {
+                if (Array.isArray(entryOrList)) {
                     for (const entry of entryOrList) {
                         if (context.moduleName) {
                             // TODO: It's probably fine to issue this diagnostic on all instances of the pragma

src/compiler/perfLogger.ts

@@ -32,7 +32,7 @@ try {
     // It may also return undefined if not installed properly
     etwModule = require(etwModulePath);
 }
-catch (e) {
+catch {
     etwModule = undefined;
 }
 

src/compiler/performanceCore.ts

@@ -116,6 +116,4 @@ export function tryGetNativePerformanceHooks() {
  *
  * @internal
  */
-export const timestamp = nativePerformance ? () => nativePerformance.now() :
-    Date.now ? Date.now :
-    () => +(new Date());
+export const timestamp = nativePerformance ? () => nativePerformance.now() : Date.now;