Instead of --jsExtensions support --allowJs with .js and .jsx as supported extensions

src/compiler/commandLineParser.ts

@@ -249,11 +249,9 @@ namespace ts {
             error: Diagnostics.Argument_for_moduleResolution_option_must_be_node_or_classic,
         },
         {
-            name: "jsExtensions",
-            type: "string[]",
-            description: Diagnostics.Specifies_extensions_to_treat_as_javascript_file_To_specify_multiple_extensions_either_use_this_option_multiple_times_or_provide_comma_separated_list,
-            paramType: Diagnostics.EXTENSION_S,
-            error: Diagnostics.Argument_for_jsExtensions_option_must_be_either_extension_or_comma_separated_list_of_extensions,
+            name: "allowJs",
+            type: "boolean",
+            description: Diagnostics.Allow_javascript_files_to_be_compiled,
         }
     ];
 

src/compiler/core.ts

@@ -729,9 +729,11 @@ namespace ts {
      *  List of supported extensions in order of file resolution precedence.
      */
     export const supportedTypeScriptExtensions = ["ts", "tsx", "d.ts"];
+    export const supportedJavascriptExtensions = ["js", "jsx"];
+    export const supportedExtensionsWhenAllowedJs = supportedTypeScriptExtensions.concat(supportedJavascriptExtensions);
 
     export function getSupportedExtensions(options?: CompilerOptions): string[] {
-        return options && options.jsExtensions ? supportedTypeScriptExtensions.concat(options.jsExtensions) : supportedTypeScriptExtensions;
+        return options && options.allowJs ? supportedExtensionsWhenAllowedJs : supportedTypeScriptExtensions;
     }
 
     export function isSupportedSourceFileName(fileName: string, compilerOptions?: CompilerOptions) {

src/compiler/diagnosticMessages.json

@@ -2181,10 +2181,6 @@
         "category": "Message",
         "code": 6038
     },
-    "EXTENSION[S]": {
-        "category": "Message",
-        "code": 6039
-    },
     "Compilation complete. Watching for file changes.": {
         "category": "Message",
         "code": 6042
@@ -2269,10 +2265,6 @@
         "category": "Error",
         "code": 6063
     },
-    "Argument for '--jsExtensions' option must be either extension or comma separated list of extensions.": {
-        "category": "Error",
-        "code": 6064
-    },
 
     "Specify JSX code generation: 'preserve' or 'react'": {
         "category": "Message",
@@ -2310,7 +2302,7 @@
         "category": "Message",
         "code": 6072
     },
-    "Specifies extensions to treat as javascript file. To specify multiple extensions, either use this option multiple times or provide comma separated list.": {
+    "Allow javascript files to be compiled.": {
         "category": "Message",
         "code": 6073
     },

src/compiler/program.ts

@@ -359,7 +359,7 @@ namespace ts {
                 (oldOptions.target !== options.target) ||
                 (oldOptions.noLib !== options.noLib) ||
                 (oldOptions.jsx !== options.jsx) ||
-                (oldOptions.jsExtensions !== options.jsExtensions)) {
+                (oldOptions.allowJs !== options.allowJs)) {
                 oldProgram = undefined;
             }
         }

src/compiler/types.ts

@@ -2089,7 +2089,7 @@ namespace ts {
         experimentalDecorators?: boolean;
         emitDecoratorMetadata?: boolean;
         moduleResolution?: ModuleResolutionKind;
-        jsExtensions?: string[];
+        allowJs?: boolean;
         /* @internal */ stripInternal?: boolean;
 
         // Skip checking lib.d.ts to help speed up tests.

src/services/services.ts

@@ -2002,7 +2002,7 @@ namespace ts {
         let getCanonicalFileName = createGetCanonicalFileName(!!useCaseSensitiveFileNames);
 
         function getKeyFromCompilationSettings(settings: CompilerOptions): string {
-            return "_" + settings.target + "|" + settings.module + "|" + settings.noResolve + "|" + settings.jsx + +"|" + settings.jsExtensions;
+            return "_" + settings.target + "|" + settings.module + "|" + settings.noResolve + "|" + settings.jsx + +"|" + settings.allowJs;
         }
 
         function getBucketForCompilationSettings(settings: CompilerOptions, createIfMissing: boolean): FileMap<DocumentRegistryEntry> {
@@ -2633,7 +2633,7 @@ namespace ts {
                  oldSettings.module !== newSettings.module ||
                  oldSettings.noResolve !== newSettings.noResolve ||
                  oldSettings.jsx !== newSettings.jsx || 
-                 oldSettings.jsExtensions !== newSettings.jsExtensions);
+                 oldSettings.allowJs !== newSettings.allowJs);
 
             // Now create a new compiler
             let compilerHost: CompilerHost = {