Enable eslint rule no-useless-escape

.eslintrc.json

@@ -103,7 +103,6 @@
         ],
 
         // Todo: For each of these, investigate whether we want to enable them ✨
-        "no-useless-escape": "off",
         "prefer-rest-params": "off",
         "prefer-spread": "off",
         "@typescript-eslint/no-empty-function": "off",

scripts/build/tests.mjs

@@ -222,5 +222,5 @@ function deleteTemporaryProjectOutput() {
  * @param {string} text
  */
 function regExpEscape(text) {
-    return text.replace(/[.*+?^${}()|\[\]\\]/g, "\\$&");
+    return text.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
 }

scripts/configurePrerelease.mjs

@@ -90,7 +90,7 @@ function updateTsFile(tsFilePath, tsFileContents, majorMinor, patch, nightlyPatc
  * @returns {{ majorMinor: string, patch: string }}
  */
 function parsePackageJsonVersion(versionString) {
-    const versionRgx = /(\d+\.\d+)\.(\d+)($|\-)/;
+    const versionRgx = /(\d+\.\d+)\.(\d+)($|-)/;
     const match = versionString.match(versionRgx);
     assert(match !== null, "package.json 'version' should match " + versionRgx.toString());
     return { majorMinor: match[1], patch: match[2] };

src/compiler/core.ts

@@ -1948,7 +1948,7 @@ export function toLowerCase(x: string) {
 //
 // But to avoid having to do string building for most common cases, also ignore
 // a-z, 0-9, \u0131, \u00DF, \, /, ., : and space
-const fileNameLowerCaseRegExp = /[^\u0130\u0131\u00DFa-z0-9\\/:\-_\. ]+/g;
+const fileNameLowerCaseRegExp = /[^\u0130\u0131\u00DFa-z0-9\\/:\-_. ]+/g;
 /**
  * Case insensitive file systems have descripencies in how they handle some characters (eg. turkish Upper case I with dot on top - \u0130)
  * This function is used in places where we want to make file name as a key on these systems

src/compiler/debug.ts

@@ -366,7 +366,7 @@ export namespace Debug {
         }
         else {
             const text = Function.prototype.toString.call(func);
-            const match = /^function\s+([\w\$]+)\s*\(/.exec(text);
+            const match = /^function\s+([\w$]+)\s*\(/.exec(text);
             return match ? match[1] : "";
         }
     }

src/compiler/emitter.ts

@@ -2493,9 +2493,9 @@ export function createPrinter(printerOptions: PrinterOptions = {}, handlers: Pri
     }
 
     function emitPlaceholder(hint: EmitHint, node: Node, snippet: Placeholder) {
-        nonEscapingWrite(`\$\{${snippet.order}:`); // `${2:`
+        nonEscapingWrite(`$\{${snippet.order}:`); // `${2:`
         pipelineEmitWithHintWorker(hint, node, /*allowSnippets*/ false); // `...`
-        nonEscapingWrite(`\}`); // `}`
+        nonEscapingWrite(`}`); // `}`
         // `${2:...}`
     }
 
@@ -2505,7 +2505,7 @@ export function createPrinter(printerOptions: PrinterOptions = {}, handlers: Pri
             `A tab stop cannot be attached to a node of kind ${Debug.formatSyntaxKind(node.kind)}.`);
         Debug.assert(hint !== EmitHint.EmbeddedStatement,
             `A tab stop cannot be attached to an embedded statement.`);
-        nonEscapingWrite(`\$${snippet.order}`);
+        nonEscapingWrite(`$${snippet.order}`);
     }
 
     //

src/compiler/scanner.ts

@@ -1516,7 +1516,7 @@ export function createScanner(languageVersion: ScriptTarget,
             case CharacterCodes.r:
                 return "\r";
             case CharacterCodes.singleQuote:
-                return "\'";
+                return "'";
             case CharacterCodes.doubleQuote:
                 return "\"";
             case CharacterCodes.u:

src/compiler/semver.ts

@@ -18,7 +18,7 @@ import {
 //
 // NOTE: We differ here in that we allow X and X.Y, with missing parts having the default
 // value of `0`.
-const versionRegExp = /^(0|[1-9]\d*)(?:\.(0|[1-9]\d*)(?:\.(0|[1-9]\d*)(?:\-([a-z0-9-.]+))?(?:\+([a-z0-9-.]+))?)?)?$/i;
+const versionRegExp = /^(0|[1-9]\d*)(?:\.(0|[1-9]\d*)(?:\.(0|[1-9]\d*)(?:-([a-z0-9-.]+))?(?:\+([a-z0-9-.]+))?)?)?$/i;
 
 // https://semver.org/#spec-item-9
 // > A pre-release version MAY be denoted by appending a hyphen and a series of dot separated
@@ -427,4 +427,4 @@ function formatAlternative(comparators: readonly Comparator[]) {
 
 function formatComparator(comparator: Comparator) {
     return `${comparator.operator}${comparator.operand}`;
-}
+}

src/compiler/utilities.ts

@@ -5813,10 +5813,10 @@ export function hasInvalidEscape(template: TemplateLiteral): boolean {
 // the language service. These characters should be escaped when printing, and if any characters are added,
 // the map below must be updated. Note that this regexp *does not* include the 'delete' character.
 // There is no reason for this other than that JSON.stringify does not handle it either.
-const doubleQuoteEscapedCharsRegExp = /[\\\"\u0000-\u001f\t\v\f\b\r\n\u2028\u2029\u0085]/g;
-const singleQuoteEscapedCharsRegExp = /[\\\'\u0000-\u001f\t\v\f\b\r\n\u2028\u2029\u0085]/g;
+const doubleQuoteEscapedCharsRegExp = /[\\"\u0000-\u001f\t\v\f\b\r\n\u2028\u2029\u0085]/g;
+const singleQuoteEscapedCharsRegExp = /[\\'\u0000-\u001f\t\v\f\b\r\n\u2028\u2029\u0085]/g;
 // Template strings preserve simple LF newlines, still encode CRLF (or CR)
-const backtickQuoteEscapedCharsRegExp = /\r\n|[\\\`\u0000-\u001f\t\v\f\b\r\u2028\u2029\u0085]/g;
+const backtickQuoteEscapedCharsRegExp = /\r\n|[\\`\u0000-\u001f\t\v\f\b\r\u2028\u2029\u0085]/g;
 const escapedCharsMap = new Map(Object.entries({
     "\t": "\\t",
     "\v": "\\v",
@@ -5826,8 +5826,8 @@ const escapedCharsMap = new Map(Object.entries({
     "\n": "\\n",
     "\\": "\\\\",
     "\"": "\\\"",
-    "\'": "\\\'",
-    "\`": "\\\`",
+    "'": "\\'",
+    "`": "\\`",
     "\u2028": "\\u2028", // lineSeparator
     "\u2029": "\\u2029", // paragraphSeparator
     "\u0085": "\\u0085", // nextLine
@@ -5883,11 +5883,11 @@ export function escapeNonAsciiString(s: string, quoteChar?: CharacterCodes.doubl
 // paragraphSeparator, and nextLine. The latter three are just desirable to suppress new lines in
 // the language service. These characters should be escaped when printing, and if any characters are added,
 // the map below must be updated.
-const jsxDoubleQuoteEscapedCharsRegExp = /[\"\u0000-\u001f\u2028\u2029\u0085]/g;
-const jsxSingleQuoteEscapedCharsRegExp = /[\'\u0000-\u001f\u2028\u2029\u0085]/g;
+const jsxDoubleQuoteEscapedCharsRegExp = /["\u0000-\u001f\u2028\u2029\u0085]/g;
+const jsxSingleQuoteEscapedCharsRegExp = /['\u0000-\u001f\u2028\u2029\u0085]/g;
 const jsxEscapedCharsMap = new Map(Object.entries({
     "\"": """,
-    "\'": "'"
+    "'": "'"
 }));
 
 function encodeJsxCharacterEntity(charCode: number): string {
@@ -8833,7 +8833,7 @@ export function tryRemoveDirectoryPrefix(path: string, dirPath: string, getCanon
 // Reserved characters, forces escaping of any non-word (or digit), non-whitespace character.
 // It may be inefficient (we could just match (/[-[\]{}()*+?.,\\^$|#\s]/g), but this is future
 // proof.
-const reservedCharacterPattern = /[^\w\s\/]/g;
+const reservedCharacterPattern = /[^\w\s/]/g;
 
 /** @internal */
 export function regExpEscape(text: string) {

src/compiler/utilitiesPublic.ts

@@ -624,7 +624,7 @@ export function validateLocaleAndSetLanguage(
     sys: { getExecutingFilePath(): string, resolvePath(path: string): string, fileExists(fileName: string): boolean, readFile(fileName: string): string | undefined },
     errors?: Diagnostic[]) {
     const lowerCaseLocale = locale.toLowerCase();
-    const matchResult = /^([a-z]+)([_\-]([a-z]+))?$/.exec(lowerCaseLocale);
+    const matchResult = /^([a-z]+)([_-]([a-z]+))?$/.exec(lowerCaseLocale);
 
     if (!matchResult) {
         if (errors) {

src/harness/fourslashImpl.ts

@@ -4912,7 +4912,7 @@ function toArray<T>(x: ArrayOrSingle<T>): readonly T[] {
 }
 
 function makeWhitespaceVisible(text: string) {
-    return text.replace(/ /g, "\u00B7").replace(/\r/g, "\u00B6").replace(/\n/g, "\u2193\n").replace(/\t/g, "\u2192\   ");
+    return text.replace(/ /g, "\u00B7").replace(/\r/g, "\u00B6").replace(/\n/g, "\u2193\n").replace(/\t/g, "\u2192   ");
 }
 
 function showTextDiff(expected: string, actual: string): string {

src/harness/harnessIO.ts

@@ -1173,8 +1173,8 @@ export namespace TestCaseParser {
     }
 
     // Regex for parsing options in the format "@Alpha: Value of any sort"
-    const optionRegex = /^[\/]{2}\s*@(\w+)\s*:\s*([^\r\n]*)/gm;  // multiple matches on multiple lines
-    const linkRegex = /^[\/]{2}\s*@link\s*:\s*([^\r\n]*)\s*->\s*([^\r\n]*)/gm;  // multiple matches on multiple lines
+    const optionRegex = /^[/]{2}\s*@(\w+)\s*:\s*([^\r\n]*)/gm;  // multiple matches on multiple lines
+    const linkRegex = /^[/]{2}\s*@link\s*:\s*([^\r\n]*)\s*->\s*([^\r\n]*)/gm;  // multiple matches on multiple lines
 
     export function parseSymlinkFromTest(line: string, symlinks: vfs.FileSet | undefined, absoluteRootDir?: string) {
         const linkMetaData = linkRegex.exec(line);

src/server/editorServices.ts

@@ -387,7 +387,7 @@ export interface TypesMapFile {
 const defaultTypeSafeList: SafeList = {
     "jquery": {
         // jquery files can have names like "jquery-1.10.2.min.js" (or "jquery.intellisense.js")
-        match: /jquery(-[\d\.]+)?(\.intellisense)?(\.min)?\.js$/i,
+        match: /jquery(-[\d.]+)?(\.intellisense)?(\.min)?\.js$/i,
         types: ["jquery"]
     },
     "WinJS": {
@@ -4008,7 +4008,7 @@ export class ProjectService {
     }
 
     /** Makes a filename safe to insert in a RegExp */
-    private static readonly filenameEscapeRegexp = /[-\/\\^$*+?.()|[\]{}]/g;
+    private static readonly filenameEscapeRegexp = /[-/\\^$*+?.()|[\]{}]/g;
     private static escapeFilenameForRegex(filename: string) {
         return filename.replace(this.filenameEscapeRegexp, "\\$&");
     }
@@ -4113,7 +4113,7 @@ export class ProjectService {
                 }
                 if (!exclude) {
                     // Exclude any minified files that get this far
-                    if (/^.+[\.-]min\.js$/.test(normalizedNames[i])) {
+                    if (/^.+[.-]min\.js$/.test(normalizedNames[i])) {
                         excludedFiles.push(normalizedNames[i]);
                     }
                     else {

src/services/codefixes/convertTypedefToType.ts

@@ -143,7 +143,7 @@ function findEndOfTextBetween(jsDocComment: JSDoc, from: number, to: number): nu
     const comment = jsDocComment.getText().substring(from - jsDocComment.getStart(), to - jsDocComment.getStart());
 
     for (let i = comment.length; i > 0; i--) {
-        if(!/[*\/\s]/g.test(comment.substring(i - 1, i))) {
+        if(!/[*/\s]/g.test(comment.substring(i - 1, i))) {
             return from + i;
         }
     }

src/services/codefixes/fixNaNEquality.ts

@@ -81,6 +81,6 @@ function doChange(changes: textChanges.ChangeTracker, sourceFile: SourceFile, ar
 }
 
 function getSuggestion(messageText: string | DiagnosticMessageChain) {
-    const [_, suggestion] = flattenDiagnosticMessageText(messageText, "\n", 0).match(/\'(.*)\'/) || [];
+    const [_, suggestion] = flattenDiagnosticMessageText(messageText, "\n", 0).match(/'(.*)'/) || [];
     return suggestion;
 }

src/services/completions.ts

@@ -3111,7 +3111,7 @@ function getCompletionData(
                 //    *         |c|
                 //    */
                 const lineStart = getLineStartPositionForPosition(position, sourceFile);
-                if (!/[^\*|\s(/)]/.test(sourceFile.text.substring(lineStart, position))) {
+                if (!/[^*|\s(/)]/.test(sourceFile.text.substring(lineStart, position))) {
                     return { kind: CompletionDataKind.JsDocTag };
                 }
             }

src/services/outliningElementsCollector.ts

@@ -165,7 +165,7 @@ function isRegionDelimiter(lineText: string) {
     // We trim the leading whitespace and // without the regex since the
     // multiple potential whitespace matches can make for some gnarly backtracking behavior
     lineText = trimStringStart(lineText);
-    if (!startsWith(lineText, "\/\/")) {
+    if (!startsWith(lineText, "//")) {
         return null; // eslint-disable-line no-null/no-null
     }
     lineText = trimString(lineText.slice(2));

src/services/services.ts

@@ -2891,7 +2891,7 @@ export function createLanguageService(
         return result;
 
         function escapeRegExp(str: string): string {
-            return str.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&");
+            return str.replace(/[-[\]/{}()*+?.\\^$|]/g, "\\$&");
         }
 
         function getTodoCommentsRegExp(): RegExp {

src/services/sourcemaps.ts

@@ -28,7 +28,7 @@ import {
     tryParseRawSourceMap,
 } from "./_namespaces/ts";
 
-const base64UrlRegExp = /^data:(?:application\/json(?:;charset=[uU][tT][fF]-8);base64,([A-Za-z0-9+\/=]+)$)?/;
+const base64UrlRegExp = /^data:(?:application\/json(?:;charset=[uU][tT][fF]-8);base64,([A-Za-z0-9+/=]+)$)?/;
 
 /** @internal */
 export interface SourceMapper {

src/testRunner/fourslashRunner.ts

@@ -53,7 +53,7 @@ export class FourSlashRunner extends RunnerBase {
                 const file = typeof test === "string" ? test : test.file;
                 describe(file, () => {
                     let fn = ts.normalizeSlashes(file);
-                    const justName = fn.replace(/^.*[\\\/]/, "");
+                    const justName = fn.replace(/^.*[\\/]/, "");
 
                     // Convert to relative path
                     const testIndex = fn.indexOf("tests/");

src/testRunner/projectsRunner.ts

@@ -137,7 +137,7 @@ class ProjectTestCase {
 
     constructor(testCaseFileName: string, { testCase, moduleKind, vfs }: ProjectTestPayload) {
         this.testCase = testCase;
-        this.testCaseJustName = testCaseFileName.replace(/^.*[\\\/]/, "").replace(/\.json/, "");
+        this.testCaseJustName = testCaseFileName.replace(/^.*[\\/]/, "").replace(/\.json/, "");
         this.compilerOptions = createCompilerOptions(testCase, moduleKind);
         this.sys = new fakes.System(vfs);
 

src/testRunner/runner.ts

@@ -53,7 +53,7 @@ function tryGetConfig(args: string[]) {
     const prefix = "--config=";
     const configPath = ts.forEach(args, arg => arg.lastIndexOf(prefix, 0) === 0 && arg.substr(prefix.length));
     // strip leading and trailing quotes from the path (necessary on Windows since shell does not do it automatically)
-    return configPath && configPath.replace(/(^[\"'])|([\"']$)/g, "");
+    return configPath && configPath.replace(/(^["'])|(["']$)/g, "");
 }
 
 export function createRunner(kind: TestRunnerKind): RunnerBase {

src/testRunner/unittests/base64.ts

@@ -10,7 +10,7 @@ describe("unittests:: base64", () => {
                 "日本語",
                 "🐱",
                 "\x00\x01",
-                "\t\n\r\\\"\'\u0062",
+                "\t\n\r\\\"'\u0062",
                 "====",
                 "",
             ];

src/testRunner/unittests/convertToBase64.ts

@@ -13,7 +13,7 @@ describe("unittests:: convertToBase64", () => {
         });
 
         it("Converts escape sequences correctly", () => {
-            runTest("\t\n\r\\\"\'\u0062");
+            runTest("\t\n\r\\\"'\u0062");
         });
 
         it("Converts simple unicode characters correctly", () => {

src/testRunner/unittests/helpers/tsserver.ts

@@ -141,8 +141,8 @@ export function createLoggerWritingToConsole(host: TestServerHost): Logger {
 
 function sanitizeLog(s: string): string {
     s = s.replace(/Elapsed::?\s*\d+(?:\.\d+)?ms/g, "Elapsed:: *ms");
-    s = s.replace(/\"updateGraphDurationMs\"\:\s*\d+(?:\.\d+)?/g, `"updateGraphDurationMs": *`);
-    s = s.replace(/\"createAutoImportProviderProgramDurationMs\"\:\s*\d+(?:\.\d+)?/g, `"createAutoImportProviderProgramDurationMs": *`);
+    s = s.replace(/"updateGraphDurationMs":\s*\d+(?:\.\d+)?/g, `"updateGraphDurationMs": *`);
+    s = s.replace(/"createAutoImportProviderProgramDurationMs":\s*\d+(?:\.\d+)?/g, `"createAutoImportProviderProgramDurationMs": *`);
     s = replaceAll(s, ts.version, "FakeVersion");
     s = s.replace(/getCompletionData: Get current token: \d+(?:\.\d+)?/g, `getCompletionData: Get current token: *`);
     s = s.replace(/getCompletionData: Is inside comment: \d+(?:\.\d+)?/g, `getCompletionData: Is inside comment: *`);
@@ -155,7 +155,7 @@ function sanitizeLog(s: string): string {
     s = s.replace(/collectAutoImports: \d+(?:\.\d+)?/g, `collectAutoImports: *`);
     s = s.replace(/continuePreviousIncompleteResponse: \d+(?:\.\d+)?/g, `continuePreviousIncompleteResponse: *`);
     s = s.replace(/dependencies in \d+(?:\.\d+)?/g, `dependencies in *`);
-    s = s.replace(/\"exportMapKey\"\:\s*\"[_$a-zA-Z][_$_$a-zA-Z0-9]*\|\d+\|/g, match => match.replace(/\|\d+\|/, `|*|`));
+    s = s.replace(/"exportMapKey":\s*"[_$a-zA-Z][_$_$a-zA-Z0-9]*\|\d+\|/g, match => match.replace(/\|\d+\|/, `|*|`));
     return s;
 }
 

src/testRunner/unittests/incrementalParser.ts

@@ -249,7 +249,7 @@ describe("unittests:: Incremental Parser", () => {
     });
 
     it("Strict mode 1", () => {
-        const source = "foo1();\r\nfoo1();\r\nfoo1();\r\package();";
+        const source = "foo1();\r\nfoo1();\r\nfoo1();\r\npackage();";
 
         const oldText = ts.ScriptSnapshot.fromString(source);
         const newTextAndChange = withInsert(oldText, 0, "'strict';\r\n");
@@ -258,7 +258,7 @@ describe("unittests:: Incremental Parser", () => {
     });
 
     it("Strict mode 2", () => {
-        const source = "foo1();\r\nfoo1();\r\nfoo1();\r\package();";
+        const source = "foo1();\r\nfoo1();\r\nfoo1();\r\npackage();";
 
         const oldText = ts.ScriptSnapshot.fromString(source);
         const newTextAndChange = withInsert(oldText, 0, "'use strict';\r\n");

src/testRunner/unittests/tsbuild/commandLine.ts

@@ -26,7 +26,7 @@ describe("unittests:: tsbuild:: commandLine::", () => {
             return {
                 ...withOptionChange(caption, option),
                 discrepancyExplanation: () => [
-                    `Clean build tsbuildinfo will have compilerOptions with composite and ${option.replace(/\-/g, "")}`,
+                    `Clean build tsbuildinfo will have compilerOptions with composite and ${option.replace(/-/g, "")}`,
                     `Incremental build will detect that it doesnt need to rebuild so tsbuild info is from before which has option composite only`,
                 ]
             };
@@ -428,4 +428,4 @@ describe("unittests:: tsbuild:: commandLine::", () => {
             baselinePrograms: true,
         });
     });
-});
+});

src/testRunner/unittests/tsc/incremental.ts

@@ -667,7 +667,7 @@ console.log(a);`,
             return {
                 ...withOptionChange(caption, option),
                 discrepancyExplanation: () => [
-                    `Clean build tsbuildinfo will have compilerOptions with composite and ${option.replace(/\-/g, "")}`,
+                    `Clean build tsbuildinfo will have compilerOptions with composite and ${option.replace(/-/g, "")}`,
                     `Incremental build will detect that it doesnt need to rebuild so tsbuild info is from before which has option composite only`,
                 ]
             };

src/testRunner/unittests/tscWatch/programUpdates.ts

@@ -1333,7 +1333,7 @@ export function two() {
     function changeParameterTypeOfBFile(parameterName: string, toType: string): TscWatchCompileChange {
         return {
             caption: `Changed ${parameterName} type to ${toType}`,
-            edit: sys => sys.replaceFileText(`/user/username/projects/myproject/b.ts`, new RegExp(`${parameterName}\: [a-z]*`), `${parameterName}: ${toType}`),
+            edit: sys => sys.replaceFileText(`/user/username/projects/myproject/b.ts`, new RegExp(`${parameterName}: [a-z]*`), `${parameterName}: ${toType}`),
             timeouts: sys => sys.runQueuedTimeoutCallbacks(),
         };
     }

src/testRunner/unittests/tsserver/cachingFileSystemInformation.ts

@@ -397,7 +397,7 @@ describe("unittests:: tsserver:: CachingFileSystemInformation:: tsserverProjectS
     "typescript"
   },
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "echo \\"Error: no test specified\\" && exit 1"
   },
   "keywords": [],
   "author": "",
@@ -483,7 +483,7 @@ describe("unittests:: tsserver:: CachingFileSystemInformation:: tsserverProjectS
             ts.forEach(filesAndFoldersToAdd, f => {
                 f.path = f.path
                     .replace("/a/b/node_modules/.staging", "/a/b/node_modules")
-                    .replace(/[\-\.][\d\w][\d\w][\d\w][\d\w][\d\w][\d\w][\d\w][\d\w]/g, "");
+                    .replace(/[-.][\d\w][\d\w][\d\w][\d\w][\d\w][\d\w][\d\w][\d\w]/g, "");
             });
 
             host.deleteFolder(root + "/a/b/node_modules/.staging", /*recursive*/ true);