Adding an outExtension option to control the file extension of emitted files

src/compiler/commandLineParser.ts

@@ -90,6 +90,7 @@ import {
     normalizeSlashes,
     NumericLiteral,
     ObjectLiteralExpression,
+    OutExtensionKind,
     ParseConfigHost,
     ParsedCommandLine,
     parseJsonText,
@@ -696,6 +697,21 @@ const commandOptionsWithoutBuild: CommandLineOption[] = [
         category: Diagnostics.Emit,
         description: Diagnostics.Specify_an_output_folder_for_all_emitted_files,
     },
+    {
+        name: "outExtension",
+        type: new Map(Object.entries({
+            input: OutExtensionKind.InferFromInput,
+            module: OutExtensionKind.InferFromModule,
+            js: OutExtensionKind.Js,
+            cjs: OutExtensionKind.Cjs,
+            mjs: OutExtensionKind.Mjs,
+        })),
+        defaultValueDescription: "input",
+        affectsEmit: true,
+        affectsBuildInfo: true,
+        category: Diagnostics.Emit,
+        description: Diagnostics.Specify_the_output_extension_for_all_emitted_files_input_will_determine_extension_based_on_the_extension_of_the_input_file_module_will_determine_extension_based_on_the_module_option,
+    },
     {
         name: "rootDir",
         type: "string",

src/compiler/diagnosticMessages.json

@@ -6099,6 +6099,10 @@
         "category": "Message",
         "code": 6718
     },
+    "Specify the output extension for all emitted files. 'input' will determine extension based on the extension of the input file. 'module' will determine extension based on the `module` option.": {
+        "category": "Message",
+        "code": 6719
+    },
     "Default catch clause variables as 'unknown' instead of 'any'.": {
         "category": "Message",
         "code": 6803

src/compiler/emitter.ts

@@ -574,6 +574,14 @@ function getSourceMapFilePath(jsFilePath: string, options: CompilerOptions) {
 export function getOutputExtension(fileName: string, options: CompilerOptions): Extension {
     return fileExtensionIs(fileName, Extension.Json) ? Extension.Json :
     options.jsx === JsxEmit.Preserve && fileExtensionIsOneOf(fileName, [Extension.Jsx, Extension.Tsx]) ? Extension.Jsx :
+    options.outExtension === ts.OutExtensionKind.InferFromModule ? (
+        options.module === ModuleKind.CommonJS ? Extension.Cjs :
+        options.module && options.module >= ModuleKind.ES2015 && options.module <= ModuleKind.ESNext ? Extension.Mjs :
+        Extension.Js
+    ) :
+    options.outExtension === ts.OutExtensionKind.Cjs ? Extension.Cjs :
+    options.outExtension === ts.OutExtensionKind.Mjs ? Extension.Mjs :
+    options.outExtension === ts.OutExtensionKind.Js ? Extension.Js :
     fileExtensionIsOneOf(fileName, [Extension.Mts, Extension.Mjs]) ? Extension.Mjs :
     fileExtensionIsOneOf(fileName, [Extension.Cts, Extension.Cjs]) ? Extension.Cjs :
     Extension.Js;

src/compiler/types.ts

@@ -7171,6 +7171,7 @@ export interface CompilerOptions {
     noUncheckedIndexedAccess?: boolean;
     out?: string;
     outDir?: string;
+    outExtension?: OutExtensionKind;
     outFile?: string;
     paths?: MapLike<string[]>;
     /**
@@ -7709,6 +7710,14 @@ export const enum Extension {
     Dcts = ".d.cts",
 }
 
+export const enum OutExtensionKind {
+    InferFromInput = 0,
+    InferFromModule = 1,
+    Js = 2,
+    Cjs = 3,
+    Mjs = 4,
+}
+
 export interface ResolvedModuleWithFailedLookupLocations {
     readonly resolvedModule: ResolvedModuleFull | undefined;
     /** @internal */

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -7231,6 +7231,7 @@ declare namespace ts {
         noUncheckedIndexedAccess?: boolean;
         out?: string;
         outDir?: string;
+        outExtension?: OutExtensionKind;
         outFile?: string;
         paths?: MapLike<string[]>;
         preserveConstEnums?: boolean;
@@ -7468,6 +7469,13 @@ declare namespace ts {
         Cts = ".cts",
         Dcts = ".d.cts"
     }
+    enum OutExtensionKind {
+        InferFromInput = 0,
+        InferFromModule = 1,
+        Js = 2,
+        Cjs = 3,
+        Mjs = 4
+    }
     interface ResolvedModuleWithFailedLookupLocations {
         readonly resolvedModule: ResolvedModuleFull | undefined;
     }

tests/baselines/reference/api/typescript.d.ts

@@ -3178,6 +3178,7 @@ declare namespace ts {
         noUncheckedIndexedAccess?: boolean;
         out?: string;
         outDir?: string;
+        outExtension?: OutExtensionKind;
         outFile?: string;
         paths?: MapLike<string[]>;
         preserveConstEnums?: boolean;
@@ -3415,6 +3416,13 @@ declare namespace ts {
         Cts = ".cts",
         Dcts = ".d.cts"
     }
+    enum OutExtensionKind {
+        InferFromInput = 0,
+        InferFromModule = 1,
+        Js = 2,
+        Cjs = 3,
+        Mjs = 4
+    }
     interface ResolvedModuleWithFailedLookupLocations {
         readonly resolvedModule: ResolvedModuleFull | undefined;
     }

tests/baselines/reference/config/initTSConfig/Default initialized TSConfig/tsconfig.json

@@ -56,6 +56,7 @@
     // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
     // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
     // "outDir": "./",                                   /* Specify an output folder for all emitted files. */
+    // "outExtension": "input",                          /* Specify the output extension for all emitted files. 'input' will determine extension based on the extension of the input file. 'module' will determine extension based on the `module` option. */
     // "removeComments": true,                           /* Disable emitting comments. */
     // "noEmit": true,                                   /* Disable emitting files from a compilation. */
     // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with --help/tsconfig.json

@@ -56,6 +56,7 @@
     // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
     // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
     // "outDir": "./",                                   /* Specify an output folder for all emitted files. */
+    // "outExtension": "input",                          /* Specify the output extension for all emitted files. 'input' will determine extension based on the extension of the input file. 'module' will determine extension based on the `module` option. */
     // "removeComments": true,                           /* Disable emitting comments. */
     // "noEmit": true,                                   /* Disable emitting files from a compilation. */
     // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with --watch/tsconfig.json

@@ -56,6 +56,7 @@
     // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
     // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
     // "outDir": "./",                                   /* Specify an output folder for all emitted files. */
+    // "outExtension": "input",                          /* Specify the output extension for all emitted files. 'input' will determine extension based on the extension of the input file. 'module' will determine extension based on the `module` option. */
     // "removeComments": true,                           /* Disable emitting comments. */
     // "noEmit": true,                                   /* Disable emitting files from a compilation. */
     // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with advanced options/tsconfig.json

@@ -56,6 +56,7 @@
     // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
     // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
     // "outDir": "./",                                   /* Specify an output folder for all emitted files. */
+    // "outExtension": "input",                          /* Specify the output extension for all emitted files. 'input' will determine extension based on the extension of the input file. 'module' will determine extension based on the `module` option. */
     // "removeComments": true,                           /* Disable emitting comments. */
     // "noEmit": true,                                   /* Disable emitting files from a compilation. */
     // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with boolean value compiler options/tsconfig.json

@@ -56,6 +56,7 @@
     // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
     // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
     // "outDir": "./",                                   /* Specify an output folder for all emitted files. */
+    // "outExtension": "input",                          /* Specify the output extension for all emitted files. 'input' will determine extension based on the extension of the input file. 'module' will determine extension based on the `module` option. */
     // "removeComments": true,                           /* Disable emitting comments. */
     // "noEmit": true,                                   /* Disable emitting files from a compilation. */
     // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with enum value compiler options/tsconfig.json

@@ -56,6 +56,7 @@
     // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
     // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
     // "outDir": "./",                                   /* Specify an output folder for all emitted files. */
+    // "outExtension": "input",                          /* Specify the output extension for all emitted files. 'input' will determine extension based on the extension of the input file. 'module' will determine extension based on the `module` option. */
     // "removeComments": true,                           /* Disable emitting comments. */
     // "noEmit": true,                                   /* Disable emitting files from a compilation. */
     // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with files options/tsconfig.json

@@ -56,6 +56,7 @@
     // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
     // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
     // "outDir": "./",                                   /* Specify an output folder for all emitted files. */
+    // "outExtension": "input",                          /* Specify the output extension for all emitted files. 'input' will determine extension based on the extension of the input file. 'module' will determine extension based on the `module` option. */
     // "removeComments": true,                           /* Disable emitting comments. */
     // "noEmit": true,                                   /* Disable emitting files from a compilation. */
     // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with incorrect compiler option value/tsconfig.json

@@ -56,6 +56,7 @@
     // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
     // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
     // "outDir": "./",                                   /* Specify an output folder for all emitted files. */
+    // "outExtension": "input",                          /* Specify the output extension for all emitted files. 'input' will determine extension based on the extension of the input file. 'module' will determine extension based on the `module` option. */
     // "removeComments": true,                           /* Disable emitting comments. */
     // "noEmit": true,                                   /* Disable emitting files from a compilation. */
     // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with incorrect compiler option/tsconfig.json

@@ -56,6 +56,7 @@
     // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
     // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
     // "outDir": "./",                                   /* Specify an output folder for all emitted files. */
+    // "outExtension": "input",                          /* Specify the output extension for all emitted files. 'input' will determine extension based on the extension of the input file. 'module' will determine extension based on the `module` option. */
     // "removeComments": true,                           /* Disable emitting comments. */
     // "noEmit": true,                                   /* Disable emitting files from a compilation. */
     // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with list compiler options with enum value/tsconfig.json

@@ -56,6 +56,7 @@
     // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
     // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
     // "outDir": "./",                                   /* Specify an output folder for all emitted files. */
+    // "outExtension": "input",                          /* Specify the output extension for all emitted files. 'input' will determine extension based on the extension of the input file. 'module' will determine extension based on the `module` option. */
     // "removeComments": true,                           /* Disable emitting comments. */
     // "noEmit": true,                                   /* Disable emitting files from a compilation. */
     // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with list compiler options/tsconfig.json

@@ -56,6 +56,7 @@
     // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
     // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
     // "outDir": "./",                                   /* Specify an output folder for all emitted files. */
+    // "outExtension": "input",                          /* Specify the output extension for all emitted files. 'input' will determine extension based on the extension of the input file. 'module' will determine extension based on the `module` option. */
     // "removeComments": true,                           /* Disable emitting comments. */
     // "noEmit": true,                                   /* Disable emitting files from a compilation. */
     // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */

tests/baselines/reference/config/showConfig/Shows tsconfig for single option/outExtension/tsconfig.json

@@ -0,0 +1,5 @@
+{
+    "compilerOptions": {
+        "outExtension": "input"
+    }
+}

tests/baselines/reference/outExtensionCjs.js

@@ -0,0 +1,51 @@
+//// [tests/cases/compiler/outExtensionCjs.ts] ////
+
+//// [input-1.ts]
+export const ts = "foo";
+
+//// [input-2.mts]
+export const mts = "foo";
+
+//// [input-3.cts]
+export const cts = "foo";
+
+//// [input-4.js]
+export const js = "foo";
+
+//// [input-5.mjs]
+export const mjs = "foo";
+
+//// [input-6.cjs]
+export const cjs = "foo";
+
+
+//// [input-1.cjs]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.ts = void 0;
+exports.ts = "foo";
+//// [input-2.cjs]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.mts = void 0;
+exports.mts = "foo";
+//// [input-3.cjs]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.cts = void 0;
+exports.cts = "foo";
+//// [input-4.cjs]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.js = void 0;
+exports.js = "foo";
+//// [input-5.cjs]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.mjs = void 0;
+exports.mjs = "foo";
+//// [input-6.cjs]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.cjs = void 0;
+exports.cjs = "foo";

tests/baselines/reference/outExtensionCjs.symbols

@@ -0,0 +1,24 @@
+=== tests/cases/compiler/input-1.ts ===
+export const ts = "foo";
+>ts : Symbol(ts, Decl(input-1.ts, 0, 12))
+
+=== tests/cases/compiler/input-2.mts ===
+export const mts = "foo";
+>mts : Symbol(mts, Decl(input-2.mts, 0, 12))
+
+=== tests/cases/compiler/input-3.cts ===
+export const cts = "foo";
+>cts : Symbol(cts, Decl(input-3.cts, 0, 12))
+
+=== tests/cases/compiler/input-4.js ===
+export const js = "foo";
+>js : Symbol(js, Decl(input-4.js, 0, 12))
+
+=== tests/cases/compiler/input-5.mjs ===
+export const mjs = "foo";
+>mjs : Symbol(mjs, Decl(input-5.mjs, 0, 12))
+
+=== tests/cases/compiler/input-6.cjs ===
+export const cjs = "foo";
+>cjs : Symbol(cjs, Decl(input-6.cjs, 0, 12))
+

tests/baselines/reference/outExtensionCjs.types

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/input-1.ts ===
+export const ts = "foo";
+>ts : "foo"
+>"foo" : "foo"
+
+=== tests/cases/compiler/input-2.mts ===
+export const mts = "foo";
+>mts : "foo"
+>"foo" : "foo"
+
+=== tests/cases/compiler/input-3.cts ===
+export const cts = "foo";
+>cts : "foo"
+>"foo" : "foo"
+
+=== tests/cases/compiler/input-4.js ===
+export const js = "foo";
+>js : "foo"
+>"foo" : "foo"
+
+=== tests/cases/compiler/input-5.mjs ===
+export const mjs = "foo";
+>mjs : "foo"
+>"foo" : "foo"
+
+=== tests/cases/compiler/input-6.cjs ===
+export const cjs = "foo";
+>cjs : "foo"
+>"foo" : "foo"
+