microsoft · jakebailey · Jan 28, 2026 · Jan 29, 2026 · Jan 30, 2026 · Jan 30, 2026
diff --git a/scripts/dtsBundler.mjs b/scripts/dtsBundler.mjs
@@ -73,7 +73,7 @@ function getDeclarationStatement(node) {
     return undefined;
 }
 
-const program = ts.createProgram([entrypoint], { target: ts.ScriptTarget.ES5 });
+const program = ts.createProgram([entrypoint], { target: ts.ScriptTarget.ES2015 });
 
 const typeChecker = program.getTypeChecker();
 

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
@@ -579,12 +579,12 @@ export const targetOptionDeclaration: CommandLineOptionOfCustomType = {
     affectsModuleResolution: true,
     affectsEmit: true,
     affectsBuildInfo: true,
-    deprecatedKeys: new Set(["es3"]),
+    deprecatedKeys: new Set(["es3", "es5"]),
     paramType: Diagnostics.VERSION,
     showInSimplifiedHelpView: true,
     category: Diagnostics.Language_and_Environment,
     description: Diagnostics.Set_the_JavaScript_language_version_for_emitted_JavaScript_and_include_compatible_library_declarations,
-    defaultValueDescription: ScriptTarget.ES5,
+    defaultValueDescription: ScriptTarget.LatestStandard,
 };
 
 /** @internal */

diff --git a/src/compiler/factory/nodeFactory.ts b/src/compiler/factory/nodeFactory.ts
@@ -6052,7 +6052,7 @@ export function createNodeFactory(flags: NodeFactoryFlags, baseFactory: BaseNode
         node.path = "" as Path;
         node.resolvedPath = "" as Path;
         node.originalFileName = "";
-        node.languageVersion = ScriptTarget.ES5;
+        node.languageVersion = ScriptTarget.LatestStandard;
         node.languageVariant = 0;
         node.scriptKind = 0;
         node.isDeclarationFile = false;

diff --git a/src/compiler/program.ts b/src/compiler/program.ts
@@ -4526,6 +4526,9 @@ export function createProgram(_rootNamesOrOptions: readonly string[] | CreatePro
         });
 
         checkDeprecations("6.0", "7.0", createDiagnostic, createDeprecatedDiagnostic => {
+            if (options.target === ScriptTarget.ES5) {
+                createDeprecatedDiagnostic("target", "ES5");
+            }
             if (options.moduleResolution === ModuleResolutionKind.Node10) {
                 createDeprecatedDiagnostic("moduleResolution", "node10", /*useInstead*/ undefined, Diagnostics.Visit_https_Colon_Slash_Slashaka_ms_Slashts6_for_migration_information);
             }

diff --git a/src/compiler/types.ts b/src/compiler/types.ts
@@ -7659,6 +7659,7 @@ export const enum ScriptKind {
 export const enum ScriptTarget {
     /** @deprecated */
     ES3 = 0,
+    /** @deprecated */
     ES5 = 1,
     ES2015 = 2,
     ES2016 = 3,
@@ -7673,6 +7674,7 @@ export const enum ScriptTarget {
     ESNext = 99,
     JSON = 100,
     Latest = ESNext,
+    LatestStandard = ES2024,
 }
 
 export const enum LanguageVariant {

diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
@@ -8991,15 +8991,10 @@ const _computedOptions = createComputedCompilerOptions({
         },
     },
     target: {
-        dependencies: ["module"],
+        dependencies: [],
         computeValue: compilerOptions => {
             const target = compilerOptions.target === ScriptTarget.ES3 ? undefined : compilerOptions.target;
-            return target ??
-                ((compilerOptions.module === ModuleKind.Node16 && ScriptTarget.ES2022) ||
-                    (compilerOptions.module === ModuleKind.Node18 && ScriptTarget.ES2022) ||
-                    (compilerOptions.module === ModuleKind.Node20 && ScriptTarget.ES2023) ||
-                    (compilerOptions.module === ModuleKind.NodeNext && ScriptTarget.ESNext) ||
-                    ScriptTarget.ES5);
+            return target ?? ScriptTarget.LatestStandard;
         },
     },
     module: {

diff --git a/src/harness/evaluatorImpl.ts b/src/harness/evaluatorImpl.ts
@@ -41,6 +41,7 @@ export function evaluateTypeScript(source: string | { files: vfs.FileSet; rootFi
         module: ts.ModuleKind.CommonJS,
         strict: false,
         lib: ["lib.esnext.d.ts", "lib.dom.d.ts"],
+        ignoreDeprecations: "6.0",
         ...options,
     };
     const host = new fakes.CompilerHost(fs, compilerOptions);

diff --git a/src/server/protocol.ts b/src/server/protocol.ts
@@ -3284,6 +3284,7 @@ export const enum NewLineKind {
 export const enum ScriptTarget {
     /** @deprecated */
     ES3 = "es3",
+    /** @deprecated */
     ES5 = "es5",
     ES6 = "es6",
     ES2015 = "es2015",
@@ -3299,6 +3300,7 @@ export const enum ScriptTarget {
     ESNext = "esnext",
     JSON = "json",
     Latest = ESNext,
+    LatestStandard = ES2024,
 }
 
 {

diff --git a/src/services/preProcess.ts b/src/services/preProcess.ts
@@ -15,7 +15,7 @@ import {
 
 export function preProcessFile(sourceText: string, readImportFiles = true, detectJavaScriptImports = false): PreProcessedFileInfo {
     const pragmaContext: PragmaContext = {
-        languageVersion: ScriptTarget.ES5, // controls whether the token scanner considers unicode identifiers or not - shouldn't matter, since we're only using it for trivia
+        languageVersion: ScriptTarget.LatestStandard, // controls whether the token scanner considers unicode identifiers or not - shouldn't matter, since we're only using it for trivia
         pragmas: undefined,
         checkJsDirective: undefined,
         referencedFiles: [],

diff --git a/src/services/services.ts b/src/services/services.ts
@@ -1382,9 +1382,8 @@ export function displayPartsToString(displayParts: SymbolDisplayPart[] | undefin
 }
 
 export function getDefaultCompilerOptions(): CompilerOptions {
-    // Always default to "ScriptTarget.ES5" for the language service
     return {
-        target: ScriptTarget.ES5,
+        target: ScriptTarget.LatestStandard,
         jsx: JsxEmit.Preserve,
     };
 }

diff --git a/src/testRunner/unittests/helpers/contents.ts b/src/testRunner/unittests/helpers/contents.ts
@@ -32,5 +32,5 @@ interface Symbol {
 `;
 
 export function getProjectConfigWithNodeNext(withNodeNext: boolean | undefined): object | undefined {
-    return withNodeNext ? { module: "nodenext", target: "es5" } : undefined;
+    return withNodeNext ? { module: "nodenext", target: "es2015" } : undefined;
 }
diff --git a/src/testRunner/unittests/helpers/demoProjectReferences.ts b/src/testRunner/unittests/helpers/demoProjectReferences.ts
@@ -92,7 +92,7 @@ export function getSysForDemoProjectReferences(): TestServerHost {
         "/user/username/projects/demo/tsconfig-base.json": jsonToReadableText({
             compilerOptions: {
                 declaration: true,
-                target: "es5",
+                target: "es2015",
                 module: "commonjs",
                 strict: true,
                 noUnusedLocals: true,

diff --git a/src/testRunner/unittests/services/convertToAsyncFunction.ts b/src/testRunner/unittests/services/convertToAsyncFunction.ts
@@ -414,6 +414,7 @@ function testConvertToAsyncFunction(it: Mocha.PendingTestFunction, caption: stri
         }
         const host = TestServerHost.createServerHost(files);
         const projectService = new TestProjectService(host);
+        projectService.setCompilerOptionsForInferredProjects({ target: ts.server.protocol.ScriptTarget.ES5 });
         projectService.openClientFile(file.path);
         return ts.first(projectService.inferredProjects).getLanguageService();
     }

diff --git a/src/testRunner/unittests/services/transpile.ts b/src/testRunner/unittests/services/transpile.ts
@@ -21,6 +21,7 @@ describe("unittests:: services:: Transpile", () => {
                 }
                 if (transpileOptions.compilerOptions.target === undefined) {
                     transpileOptions.compilerOptions.target = ts.ScriptTarget.ES5;
+                    transpileOptions.compilerOptions.ignoreDeprecations = "6.0";
                 }
 
                 if (transpileOptions.compilerOptions.newLine === undefined) {
@@ -204,6 +205,7 @@ var x = 0;`,
                     emitDecoratorMetadata: true,
                     experimentalDecorators: true,
                     target: ts.ScriptTarget.ES5,
+                    ignoreDeprecations: "6.0",
                 },
             },
             testVerbatimModuleSyntax: true,

diff --git a/src/testRunner/unittests/tsbuild/emitDeclarationOnly.ts b/src/testRunner/unittests/tsbuild/emitDeclarationOnly.ts
@@ -35,7 +35,7 @@ describe("unittests:: tsbuild:: on project with emitDeclarationOnly:: set to tru
             "/home/src/workspaces/project/tsconfig.json": jsonToReadableText({
                 compilerOptions: {
                     incremental: true,
-                    target: "es5",
+                    target: "es2015",
                     module: "commonjs",
                     declaration: true,
                     declarationMap: true,

diff --git a/src/testRunner/unittests/tsbuild/inferredTypeFromTransitiveModule.ts b/src/testRunner/unittests/tsbuild/inferredTypeFromTransitiveModule.ts
@@ -50,7 +50,7 @@ describe("unittests:: tsbuild:: inferredTypeFromTransitiveModule::", () => {
             `,
             "/home/src/workspaces/project/tsconfig.json": jsonToReadableText({
                 compilerOptions: {
-                    target: "es5",
+                    target: "es2015",
                     declaration: true,
                     outDir: "obj",
                     incremental: true,

diff --git a/src/testRunner/unittests/tsbuild/resolveJsonModule.ts b/src/testRunner/unittests/tsbuild/resolveJsonModule.ts
@@ -178,7 +178,7 @@ describe("unittests:: tsbuild:: with resolveJsonModule:: option on project impor
                 }),
                 "/home/src/workspaces/solution/project/tsconfig.json": jsonToReadableText({
                     compilerOptions: {
-                        target: "es5",
+                        target: "es2015",
                         module: "commonjs",
                         rootDir: "./",
                         composite: true,

diff --git a/src/testRunner/unittests/tsbuild/sample.ts b/src/testRunner/unittests/tsbuild/sample.ts
@@ -1,5 +1,6 @@
 import { Baseline } from "../../_namespaces/Harness.js";
 import * as ts from "../../_namespaces/ts.js";
+import { dedent } from "../../_namespaces/Utils.js";
 import { jsonToReadableText } from "../helpers.js";
 import {
     fakeTsVersion,
@@ -241,7 +242,7 @@ describe("unittests:: tsbuild:: on 'sample1' project", () => {
             sys: getSysForSampleProjectReferences,
             commandLineArgs: ["--b", "tests", "--verbose"],
             modifySystem: sys => {
-                sys.writeFile("tests/tsconfig.base.json", jsonToReadableText({ compilerOptions: { target: "es5" } }));
+                sys.writeFile("tests/tsconfig.base.json", jsonToReadableText({ compilerOptions: { target: "es2015" } }));
                 sys.replaceFileText("tests/tsconfig.json", `"references": [`, `"extends": "./tsconfig.base.json", "references": [`);
             },
             edits: [{
@@ -510,6 +511,15 @@ class someClass2 { }`,
                     libFile.path,
                     `/// <reference lib="esnext" />`,
                 );
+                sys.writeFile(
+                    "core/index.ts",
+                    dedent`
+                        export const someString: string = "HELLO WORLD";
+                        export function leftPad(s: string, n: number) { return s + n; }
+                        export function multiply(a: number, b: number) { return a * b; }
+                        export function exponentiate(a: number, b: number) { return a ** b; }
+                    `,
+                );
                 sys.writeFile(
                     "core/tsconfig.json",
                     jsonToReadableText({
@@ -524,7 +534,7 @@ class someClass2 { }`,
             },
             edits: [{
                 caption: "incremental-declaration-changes",
-                edit: sys => sys.replaceFileText("core/tsconfig.json", "esnext", "es5"),
+                edit: sys => sys.replaceFileText("core/tsconfig.json", "esnext", "es2015"),
             }],
         });
 

diff --git a/src/testRunner/unittests/tsc/composite.ts b/src/testRunner/unittests/tsc/composite.ts
@@ -13,7 +13,7 @@ describe("unittests:: tsc:: composite::", () => {
                 "/home/src/workspaces/project/src/main.ts": "export const x = 10;",
                 "/home/src/workspaces/project/tsconfig.json": jsonToReadableText({
                     compilerOptions: {
-                        target: "es5",
+                        target: "es2015",
                         module: "commonjs",
                         composite: true,
                     },
@@ -33,7 +33,7 @@ describe("unittests:: tsc:: composite::", () => {
                 "/home/src/workspaces/project/src/main.ts": "export const x = 10;",
                 "/home/src/workspaces/project/tsconfig.json": jsonToReadableText({
                     compilerOptions: {
-                        target: "es5",
+                        target: "es2015",
                         module: "commonjs",
                         composite: true,
                     },
@@ -53,7 +53,7 @@ describe("unittests:: tsc:: composite::", () => {
                 "/home/src/workspaces/project/src/main.ts": "export const x = 10;",
                 "/home/src/workspaces/project/tsconfig.json": jsonToReadableText({
                     compilerOptions: {
-                        target: "es5",
+                        target: "es2015",
                         module: "commonjs",
                         composite: true,
                         tsBuildInfoFile: "tsconfig.json.tsbuildinfo",
@@ -74,7 +74,7 @@ describe("unittests:: tsc:: composite::", () => {
                 "/home/src/workspaces/project/src/main.ts": "export const x = 10;",
                 "/home/src/workspaces/project/tsconfig.json": jsonToReadableText({
                     compilerOptions: {
-                        target: "es5",
+                        target: "es2015",
                         module: "commonjs",
                         composite: true,
                         tsBuildInfoFile: "tsconfig.json.tsbuildinfo",

diff --git a/src/testRunner/unittests/tsc/declarationEmit.ts b/src/testRunner/unittests/tsc/declarationEmit.ts
@@ -55,7 +55,7 @@ describe("unittests:: tsc:: declarationEmit::", () => {
             function pluginOneConfig() {
                 return jsonToReadableText({
                     compilerOptions: {
-                        target: "es5",
+                        target: "es2015",
                         declaration: true,
                         traceResolution: true,
                     },
@@ -236,7 +236,7 @@ ${pluginOneAction()}`,
                         compilerOptions: {
                             outDir: "dist",
                             rootDir: "src",
-                            target: "es5",
+                            target: "es2015",
                             module: "commonjs",
                             strict: true,
                             esModuleInterop: true,

diff --git a/src/testRunner/unittests/tsc/incremental.ts b/src/testRunner/unittests/tsc/incremental.ts
@@ -23,7 +23,7 @@ describe("unittests:: tsc:: incremental::", () => {
                 "/home/src/workspaces/project/src/main.ts": "export const x = 10;",
                 "/home/src/workspaces/project/tsconfig.json": jsonToReadableText({
                     compilerOptions: {
-                        target: "es5",
+                        target: "es2015",
                         module: "commonjs",
                     },
                     include: [

diff --git a/src/testRunner/unittests/tscWatch/incremental.ts b/src/testRunner/unittests/tscWatch/incremental.ts
@@ -157,7 +157,7 @@ describe("unittests:: tscWatch:: incremental:: emit file --incremental", () => {
                     { currentDirectory: project },
                 );
                 const reportDiagnostic = ts.createDiagnosticReporter(system);
-                const parsedConfig = ts.parseConfigFileWithSystem("tsconfig.json", {}, /*extendedConfigCache*/ undefined, /*watchOptionsToExtend*/ undefined, system, reportDiagnostic)!;
+                const parsedConfig = ts.parseConfigFileWithSystem("tsconfig.json", { target: ts.ScriptTarget.ES5, module: ts.ModuleKind.AMD }, /*extendedConfigCache*/ undefined, /*watchOptionsToExtend*/ undefined, system, reportDiagnostic)!;
                 ts.performIncrementalCompilation({
                     rootNames: parsedConfig.fileNames,
                     options: parsedConfig.options,
@@ -167,7 +167,7 @@ describe("unittests:: tscWatch:: incremental:: emit file --incremental", () => {
                     system,
                 });
 
-                const command = ts.parseConfigFileWithSystem("tsconfig.json", {}, /*extendedConfigCache*/ undefined, /*watchOptionsToExtend*/ undefined, system, ts.noop)!;
+                const command = ts.parseConfigFileWithSystem("tsconfig.json", { target: ts.ScriptTarget.ES5, module: ts.ModuleKind.AMD }, /*extendedConfigCache*/ undefined, /*watchOptionsToExtend*/ undefined, system, ts.noop)!;
                 const builderProgram = ts.createIncrementalProgram({
                     rootNames: command.fileNames,
                     options: command.options,
@@ -200,6 +200,7 @@ describe("unittests:: tscWatch:: incremental:: emit file --incremental", () => {
 
                 assert.deepEqual(builderProgram.state.compilerOptions, {
                     incremental: true,
+                    target: ts.ScriptTarget.ES5,
                     module: ts.ModuleKind.AMD,
                     configFilePath: config.path,
                     ignoreDeprecations: "6.0",
@@ -242,7 +243,7 @@ describe("unittests:: tscWatch:: incremental:: emit file --incremental", () => {
                 content: jsonToReadableText({
                     compilerOptions: {
                         incremental: true,
-                        target: "es5",
+                        target: "es2015",
                         module: "commonjs",
                         declaration: true,
                         emitDeclarationOnly: true,

diff --git a/src/testRunner/unittests/tscWatch/programUpdates.ts b/src/testRunner/unittests/tscWatch/programUpdates.ts
@@ -985,7 +985,7 @@ declare const eval: any`,
                     {
                         compilerOptions: {
                             module: "commonjs",
-                            target: "es5",
+                            target: "es2015",
                             noImplicitAny: true,
                             sourceMap: false,
                             lib: [
@@ -1010,7 +1010,7 @@ declare const eval: any`,
                             {
                                 compilerOptions: {
                                     module: "commonjs",
-                                    target: "es5",
+                                    target: "es2015",
                                     noImplicitAny: true,
                                     sourceMap: false,
                                     lib: [

diff --git a/tests/baselines/reference/ES3For-ofTypeCheck1(target=es5).errors.txt b/tests/baselines/reference/ES3For-ofTypeCheck1(target=es5).errors.txt
@@ -0,0 +1,6 @@
+error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+
+
+!!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+==== ES3For-ofTypeCheck1.ts (0 errors) ====
+    for (var v of "") { }
diff --git a/tests/baselines/reference/ES3For-ofTypeCheck2(target=es5).errors.txt b/tests/baselines/reference/ES3For-ofTypeCheck2(target=es5).errors.txt
@@ -0,0 +1,6 @@
+error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+
+
+!!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+==== ES3For-ofTypeCheck2.ts (0 errors) ====
+    for (var v of [true]) { }
diff --git a/tests/baselines/reference/ES3For-ofTypeCheck4(target=es5).errors.txt b/tests/baselines/reference/ES3For-ofTypeCheck4(target=es5).errors.txt
@@ -0,0 +1,7 @@
+error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+
+
+!!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+==== ES3For-ofTypeCheck4.ts (0 errors) ====
+    var union: string | string[];
+    for (const v of union) { }
diff --git a/tests/baselines/reference/ES3For-ofTypeCheck6(target=es5).errors.txt b/tests/baselines/reference/ES3For-ofTypeCheck6(target=es5).errors.txt
@@ -0,0 +1,7 @@
+error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+
+
+!!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+==== ES3For-ofTypeCheck6.ts (0 errors) ====
+    var union: string[] | number[];
+    for (var v of union) { }
diff --git a/tests/baselines/reference/ES5For-of1(target=es5).errors.txt b/tests/baselines/reference/ES5For-of1(target=es5).errors.txt
@@ -0,0 +1,8 @@
+error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+
+
+!!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+==== ES5For-of1.ts (0 errors) ====
+    for (var v of ['a', 'b', 'c']) {
+        console.log(v);
+    }