microsoft · SMotaal · Apr 25, 2018 · Apr 25, 2018
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
@@ -743,9 +743,9 @@ namespace ts {
     export function deduplicate<T>(array: ReadonlyArray<T>, equalityComparer: EqualityComparer<T>, comparer?: Comparer<T>): T[] {
         return !array ? undefined :
             array.length === 0 ? [] :
-            array.length === 1 ? array.slice() :
-            comparer ? deduplicateRelational(array, equalityComparer, comparer) :
-            deduplicateEquality(array, equalityComparer);
+                array.length === 1 ? array.slice() :
+                    comparer ? deduplicateRelational(array, equalityComparer, comparer) :
+                        deduplicateEquality(array, equalityComparer);
     }
 
     /**
@@ -1008,15 +1008,17 @@ namespace ts {
 
     export function arrayIterator<T>(array: ReadonlyArray<T>): Iterator<T> {
         let i = 0;
-        return { next: () => {
-            if (i === array.length) {
-                return { value: undefined as never, done: true };
-            }
-            else {
-                i++;
-                return { value: array[i - 1], done: false };
+        return {
+            next: () => {
+                if (i === array.length) {
+                    return { value: undefined as never, done: true };
+                }
+                else {
+                    i++;
+                    return { value: array[i - 1], done: false };
+                }
             }
-        }};
+        };
     }
 
     /**
@@ -1710,9 +1712,9 @@ namespace ts {
     function compareComparableValues(a: string | number, b: string | number) {
         return a === b ? Comparison.EqualTo :
             a === undefined ? Comparison.LessThan :
-            b === undefined ? Comparison.GreaterThan :
-            a < b ? Comparison.LessThan :
-            Comparison.GreaterThan;
+                b === undefined ? Comparison.GreaterThan :
+                    a < b ? Comparison.LessThan :
+                        Comparison.GreaterThan;
     }
 
     /**
@@ -1882,8 +1884,8 @@ namespace ts {
     export function compareProperties<T, K extends keyof T>(a: T, b: T, key: K, comparer: Comparer<T[K]>) {
         return a === b ? Comparison.EqualTo :
             a === undefined ? Comparison.LessThan :
-            b === undefined ? Comparison.GreaterThan :
-            comparer(a[key], b[key]);
+                b === undefined ? Comparison.GreaterThan :
+                    comparer(a[key], b[key]);
     }
 
     function getDiagnosticFileName(diagnostic: Diagnostic): string {
@@ -2036,7 +2038,7 @@ namespace ts {
         return compilerOptions.target || ScriptTarget.ES3;
     }
 
-    export function getEmitModuleKind(compilerOptions: {module?: CompilerOptions["module"], target?: CompilerOptions["target"]}) {
+    export function getEmitModuleKind(compilerOptions: { module?: CompilerOptions["module"], target?: CompilerOptions["target"] }) {
         return typeof compilerOptions.module === "number" ?
             compilerOptions.module :
             getEmitScriptTarget(compilerOptions) >= ScriptTarget.ES2015 ? ModuleKind.ES2015 : ModuleKind.CommonJS;
@@ -2653,6 +2655,8 @@ namespace ts {
     export function getScriptKindFromFileName(fileName: string): ScriptKind {
         const ext = fileName.substr(fileName.lastIndexOf("."));
         switch (ext.toLowerCase()) {
+            case Extension.Mjs:
+                return ScriptKind.JS;
             case Extension.Js:
                 return ScriptKind.JS;
             case Extension.Jsx:
@@ -2674,7 +2678,7 @@ namespace ts {
     export const supportedTypeScriptExtensions: ReadonlyArray<Extension> = [Extension.Ts, Extension.Tsx, Extension.Dts];
     /** Must have ".d.ts" first because if ".ts" goes first, that will be detected as the extension instead of ".d.ts". */
     export const supportedTypescriptExtensionsForExtractExtension: ReadonlyArray<Extension> = [Extension.Dts, Extension.Ts, Extension.Tsx];
-    export const supportedJavascriptExtensions: ReadonlyArray<Extension> = [Extension.Js, Extension.Jsx];
+    export const supportedJavascriptExtensions: ReadonlyArray<Extension> = [Extension.Mjs, Extension.Js, Extension.Jsx];
     const allSupportedExtensions: ReadonlyArray<Extension> = [...supportedTypeScriptExtensions, ...supportedJavascriptExtensions];
 
     export function getSupportedExtensions(options?: CompilerOptions, extraFileExtensions?: ReadonlyArray<JsFileExtensionInfo>): ReadonlyArray<string> {
@@ -2760,7 +2764,7 @@ namespace ts {
         }
     }
 
-    const extensionsToRemove = [Extension.Dts, Extension.Ts, Extension.Js, Extension.Tsx, Extension.Jsx];
+    const extensionsToRemove = [Extension.Dts, Extension.Ts, Extension.Mjs, Extension.Js, Extension.Tsx, Extension.Jsx];
     export function removeFileExtension(path: string): string {
         for (const ext of extensionsToRemove) {
             const extensionless = tryRemoveExtension(path, ext);
@@ -2822,7 +2826,7 @@ namespace ts {
         }
     }
 
-    function Signature() {} // tslint:disable-line no-empty
+    function Signature() { } // tslint:disable-line no-empty
 
     function Node(this: Node, kind: SyntaxKind, pos: number, end: number) {
         this.pos = pos;

diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
@@ -77,7 +77,11 @@ namespace ts {
                 return Extension.Jsx;
             }
         }
-        return Extension.Js;
+        return options.target === ScriptTarget.ESNext
+            && options.module === ModuleKind.ESNext
+            && options.esModuleInterop
+            && options.allowSyntheticDefaultImports
+            && Extension.Mjs || Extension.Js;
     }
 
     /*@internal*/
@@ -3236,10 +3240,10 @@ namespace ts {
                     pushNameGenerationScope(/*node*/ undefined);
                     tempFlags = savedTempFlags;
                     return result;
-                  }
-                  else {
+                }
+                else {
                     return generateNameCached(getNodeForGeneratedName(name));
-                  }
+                }
             }
             else {
                 // Auto, Loop, and Unique names are cached based on their unique

diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
@@ -932,7 +932,7 @@ namespace ts {
             case Extensions.TypeScript:
                 return tryExtension(Extension.Ts) || tryExtension(Extension.Tsx) || tryExtension(Extension.Dts);
             case Extensions.JavaScript:
-                return tryExtension(Extension.Js) || tryExtension(Extension.Jsx);
+                return tryExtension(Extension.Mjs) || tryExtension(Extension.Js) || tryExtension(Extension.Jsx);
         }
 
         function tryExtension(ext: Extension): PathAndExtension | undefined {
@@ -996,7 +996,7 @@ namespace ts {
                 else {
                     const jsPath = tryReadPackageJsonFields(/*readTypes*/ false, packageJsonContent, nodeModuleDirectory, state);
                     if (typeof jsPath === "string") {
-                        subModuleName = removeExtension(removeExtension(jsPath.substring(nodeModuleDirectory.length + 1), Extension.Js), Extension.Jsx) + Extension.Dts;
+                        subModuleName = removeExtension(removeExtension(removeExtension(jsPath.substring(nodeModuleDirectory.length + 1), Extension.Mjs), Extension.Js), Extension.Jsx) + Extension.Dts;
                     }
                     else {
                         subModuleName = "index.d.ts";
@@ -1068,7 +1068,7 @@ namespace ts {
     function extensionIsOk(extensions: Extensions, extension: Extension): boolean {
         switch (extensions) {
             case Extensions.JavaScript:
-                return extension === Extension.Js || extension === Extension.Jsx;
+                return extension === Extension.Mjs || extension === Extension.Js || extension === Extension.Jsx;
             case Extensions.TypeScript:
                 return extension === Extension.Ts || extension === Extension.Tsx || extension === Extension.Dts;
             case Extensions.DtsOnly:

diff --git a/src/compiler/program.ts b/src/compiler/program.ts
@@ -328,14 +328,14 @@ namespace ts {
 
                 output += formatColorAndReset(relativeFileName, ForegroundColorEscapeSequences.Cyan);
                 output += ":";
-                output += formatColorAndReset(`${ firstLine + 1 }`, ForegroundColorEscapeSequences.Yellow);
+                output += formatColorAndReset(`${firstLine + 1}`, ForegroundColorEscapeSequences.Yellow);
                 output += ":";
-                output += formatColorAndReset(`${ firstLineChar + 1 }`, ForegroundColorEscapeSequences.Yellow);
+                output += formatColorAndReset(`${firstLineChar + 1}`, ForegroundColorEscapeSequences.Yellow);
                 output += " - ";
             }
 
             output += formatColorAndReset(diagnosticCategoryName(diagnostic), getCategoryFormat(diagnostic.category));
-            output += formatColorAndReset(` TS${ diagnostic.code }: `, ForegroundColorEscapeSequences.Grey);
+            output += formatColorAndReset(` TS${diagnostic.code}: `, ForegroundColorEscapeSequences.Grey);
             output += flattenDiagnosticMessageText(diagnostic.messageText, host.getNewLine());
 
             if (diagnostic.file) {
@@ -2428,6 +2428,7 @@ namespace ts {
                 return needJsx();
             case Extension.Jsx:
                 return needJsx() || needAllowJs();
+            case Extension.Mjs:
             case Extension.Js:
                 return needAllowJs();
         }

diff --git a/src/compiler/resolutionCache.ts b/src/compiler/resolutionCache.ts
@@ -103,7 +103,7 @@ namespace ts {
          * This helps in not having to comb through all resolutions when files are added/removed
          * Note that .d.ts file also has .d.ts extension hence will be part of default extensions
          */
-        const failedLookupDefaultExtensions = [Extension.Ts, Extension.Tsx, Extension.Js, Extension.Jsx, Extension.Json];
+        const failedLookupDefaultExtensions = [Extension.Ts, Extension.Tsx, Extension.Mjs, Extension.Js, Extension.Jsx, Extension.Json];
         const customFailedLookupPaths = createMap<number>();
 
         const directoryWatchesOfFailedLookups = createMap<DirectoryWatchesOfFailedLookup>();

diff --git a/src/compiler/types.ts b/src/compiler/types.ts
@@ -4583,6 +4583,7 @@ namespace ts {
         Ts = ".ts",
         Tsx = ".tsx",
         Dts = ".d.ts",
+        Mjs = ".mjs",
         Js = ".js",
         Jsx = ".jsx",
         Json = ".json"

diff --git a/src/harness/harness.ts b/src/harness/harness.ts
@@ -159,7 +159,7 @@ namespace Utils {
     export function memoize<T extends ts.AnyFunction>(f: T, memoKey: (...anything: any[]) => string): T {
         const cache = ts.createMap<any>();
 
-        return <any>(function(this: any, ...args: any[]) {
+        return <any>(function (this: any, ...args: any[]) {
             const key = memoKey(...args);
             if (cache.has(key)) {
                 return cache.get(key);
@@ -1343,7 +1343,7 @@ namespace Harness {
         export function getErrorBaseline(inputFiles: ReadonlyArray<TestFile>, diagnostics: ReadonlyArray<ts.Diagnostic>, pretty?: boolean) {
             let outputLines = "";
             const gen = iterateErrorBaseline(inputFiles, diagnostics, pretty);
-            for (let {done, value} = gen.next(); !done; { done, value } = gen.next()) {
+            for (let { done, value } = gen.next(); !done; { done, value } = gen.next()) {
                 const [, content] = value;
                 outputLines += content;
             }
@@ -1352,7 +1352,7 @@ namespace Harness {
 
         export const diagnosticSummaryMarker = "__diagnosticSummary";
         export const globalErrorsMarker = "__globalErrors";
-        export function *iterateErrorBaseline(inputFiles: ReadonlyArray<TestFile>, diagnostics: ReadonlyArray<ts.Diagnostic>, pretty?: boolean): IterableIterator<[string, string, number]> {
+        export function* iterateErrorBaseline(inputFiles: ReadonlyArray<TestFile>, diagnostics: ReadonlyArray<ts.Diagnostic>, pretty?: boolean): IterableIterator<[string, string, number]> {
             diagnostics = ts.sort(diagnostics, ts.compareDiagnostics);
             let outputLines = "";
             // Count up all errors that were found in files other than lib.d.ts so we don't miss any
@@ -1496,7 +1496,7 @@ namespace Harness {
             });
         }
 
-        export function doTypeAndSymbolBaseline(baselinePath: string, program: ts.Program, allFiles: {unitName: string, content: string}[], opts?: Baseline.BaselineOptions, multifile?: boolean, skipTypeBaselines?: boolean, skipSymbolBaselines?: boolean) {
+        export function doTypeAndSymbolBaseline(baselinePath: string, program: ts.Program, allFiles: { unitName: string, content: string }[], opts?: Baseline.BaselineOptions, multifile?: boolean, skipTypeBaselines?: boolean, skipSymbolBaselines?: boolean) {
             // The full walker simulates the types that you would get from doing a full
             // compile.  The pull walker simulates the types you get when you just do
             // a type query for a random node (like how the LS would do it).  Most of the
@@ -1567,7 +1567,7 @@ namespace Harness {
             function generateBaseLine(isSymbolBaseline: boolean, skipBaseline?: boolean): string {
                 let result = "";
                 const gen = iterateBaseLine(isSymbolBaseline, skipBaseline);
-                for (let {done, value} = gen.next(); !done; { done, value } = gen.next()) {
+                for (let { done, value } = gen.next(); !done; { done, value } = gen.next()) {
                     const [, content] = value;
                     result += content;
                 }
@@ -1576,7 +1576,7 @@ namespace Harness {
                 /* tslint:enable:no-null-keyword */
             }
 
-            function *iterateBaseLine(isSymbolBaseline: boolean, skipBaseline?: boolean): IterableIterator<[string, string]> {
+            function* iterateBaseLine(isSymbolBaseline: boolean, skipBaseline?: boolean): IterableIterator<[string, string]> {
                 if (skipBaseline) {
                     return;
                 }
@@ -1588,7 +1588,7 @@ namespace Harness {
                     const codeLines = ts.flatMap(file.content.split(/\r?\n/g), e => e.split(/[\r\u2028\u2029]/g));
                     const gen: IterableIterator<TypeWriterResult> = isSymbolBaseline ? fullWalker.getSymbols(unitName) : fullWalker.getTypes(unitName);
                     let lastIndexWritten: number | undefined;
-                    for (let {done, value: result} = gen.next(); !done; { done, value: result } = gen.next()) {
+                    for (let { done, value: result } = gen.next(); !done; { done, value: result } = gen.next()) {
                         if (isSymbolBaseline && !result.symbol) {
                             return;
                         }
@@ -1644,7 +1644,14 @@ namespace Harness {
                     throw new Error("Number of sourcemap files should be same as js files.");
                 }
 
-                Baseline.runBaseline(baselinePath.replace(/\.tsx?/, ".js.map"), () => {
+                const outExt = options.target === ts.ScriptTarget.ESNext
+                    && options.module === ts.ModuleKind.ESNext
+                    && options.esModuleInterop
+                    && options.allowSyntheticDefaultImports
+                    ? ts.Extension.Mjs : ts.Extension.Js;
+                const mapExt = `${outExt}.map`;
+
+                Baseline.runBaseline(baselinePath.replace(/\.tsx?/, mapExt), () => {
                     if ((options.noEmitOnError && result.errors.length !== 0) || result.sourceMaps.length === 0) {
                         // We need to return null here or the runBaseLine will actually create a empty file.
                         // Baselining isn't required here because there is no output.
@@ -1668,8 +1675,11 @@ namespace Harness {
                 throw new Error("Expected at least one js file to be emitted or at least one error to be created.");
             }
 
+            const outExt = options.target === ts.ScriptTarget.ESNext
+                ? ts.Extension.Mjs : ts.Extension.Js;
+
             // check js output
-            Baseline.runBaseline(baselinePath.replace(/\.tsx?/, ts.Extension.Js), () => {
+            Baseline.runBaseline(baselinePath.replace(/\.tsx?/, outExt), () => {
                 let tsCode = "";
                 const tsSources = otherFiles.concat(toBeCompiled);
                 if (tsSources.length > 1) {
@@ -1723,7 +1733,7 @@ namespace Harness {
             const gen = iterateOutputs(outputFiles);
             // Emit them
             let result = "";
-            for (let {done, value} = gen.next(); !done; { done, value } = gen.next()) {
+            for (let { done, value } = gen.next(); !done; { done, value } = gen.next()) {
                 // Some extra spacing if this isn't the first file
                 if (result.length) {
                     result += "\r\n\r\n";
@@ -1735,7 +1745,7 @@ namespace Harness {
             return result;
         }
 
-        export function *iterateOutputs(outputFiles: GeneratedFile[]): IterableIterator<[string, string]> {
+        export function* iterateOutputs(outputFiles: GeneratedFile[]): IterableIterator<[string, string]> {
             // Collect, test, and sort the fileNames
             outputFiles.sort((a, b) => ts.compareStringsCaseSensitive(cleanName(a.fileName), cleanName(b.fileName)));
             const dupeCase = ts.createMap<number>();
@@ -1797,14 +1807,17 @@ namespace Harness {
         }
 
         export function isJS(fileName: string) {
-            return ts.endsWith(fileName, ts.Extension.Js);
+            return ts.endsWith(fileName, ts.Extension.Mjs)
+                || ts.endsWith(fileName, ts.Extension.Js);
         }
         export function isJSX(fileName: string) {
             return ts.endsWith(fileName, ts.Extension.Jsx);
         }
 
         export function isJSMap(fileName: string) {
-            return ts.endsWith(fileName, ".js.map") || ts.endsWith(fileName, ".jsx.map");
+            return ts.endsWith(fileName, ".mjs.map")
+                || ts.endsWith(fileName, ".js.map")
+                || ts.endsWith(fileName, ".jsx.map");
         }
 
         export function isDTSMap(fileName: string) {
@@ -1874,7 +1887,7 @@ namespace Harness {
             let match: RegExpExecArray;
             /* tslint:disable:no-null-keyword */
             while ((match = optionRegex.exec(content)) !== null) {
-            /* tslint:enable:no-null-keyword */
+                /* tslint:enable:no-null-keyword */
                 opts[match[1]] = match[2].trim();
             }
 
@@ -2056,7 +2069,7 @@ namespace Harness {
 
             /* tslint:disable:no-null-keyword */
             if (actual === null) {
-            /* tslint:enable:no-null-keyword */
+                /* tslint:enable:no-null-keyword */
                 actual = noContent;
             }
 
@@ -2119,7 +2132,7 @@ namespace Harness {
             const errors: Error[] = [];
             // tslint:disable-next-line:no-null-keyword
             if (gen !== null) {
-                for (let {done, value} = gen.next(); !done; { done, value } = gen.next()) {
+                for (let { done, value } = gen.next(); !done; { done, value } = gen.next()) {
                     const [name, content, count] = value as [string, string, number | undefined];
                     if (count === 0) continue; // Allow error reporter to skip writing files without errors
                     const relativeFileName = relativeFileBase + "/" + name + extension;