Merge pull request #2547 from Microsoft/exportDefault

Export default fixes

Author: ahejlsberg

src/compiler/emitter.ts

@@ -2424,11 +2424,11 @@ module ts {
                 if (node.flags & NodeFlags.Export) {
                     writeLine();
                     emitStart(node);
-                    if (node.name) {
-                        emitModuleMemberName(node);
+                    if (node.flags & NodeFlags.Default) {
+                        write("exports.default");
                     }
                     else {
-                        write("exports.default");
+                        emitModuleMemberName(node);
                     }
                     write(" = ");
                     emitDeclarationName(node);
@@ -2919,16 +2919,14 @@ module ts {
                 }
             }
 
-            function shouldEmitFunctionName(node: Declaration): boolean {
-                // Emit a declaration name for the function iff:
-                //    it is a function expression with a name provided
-                //    it is a function declaration with a name provided
-                //    it is a function declaration is not the default export, and is missing a name (emit a generated name for it)
+            function shouldEmitFunctionName(node: FunctionLikeDeclaration) {
                 if (node.kind === SyntaxKind.FunctionExpression) {
+                    // Emit name if one is present
                     return !!node.name;
                 }
-                else if (node.kind === SyntaxKind.FunctionDeclaration) {
-                    return !!node.name || (languageVersion >= ScriptTarget.ES6 && !(node.flags & NodeFlags.Default));
+                if (node.kind === SyntaxKind.FunctionDeclaration) {
+                    // Emit name if one is present, or emit generated name in down-level case (for export default case)
+                    return !!node.name || languageVersion < ScriptTarget.ES6;
                 }
             }
 

tests/baselines/reference/es5ExportDefaultClassDeclaration.js

@@ -12,7 +12,7 @@ var C = (function () {
     C.prototype.method = function () { };
     return C;
 })();
-exports.C = C;
+exports.default = C;
 
 
 //// [es5ExportDefaultClassDeclaration.d.ts]

tests/baselines/reference/es5ExportDefaultFunctionDeclaration.js

@@ -5,7 +5,7 @@ export default function f() { }
 
 //// [es5ExportDefaultFunctionDeclaration.js]
 function f() { }
-exports.f = f;
+exports.default = f;
 
 
 //// [es5ExportDefaultFunctionDeclaration.d.ts]

tests/baselines/reference/es5ExportDefaultFunctionDeclaration2.js

@@ -4,7 +4,7 @@ export default function () { }
 
 
 //// [es5ExportDefaultFunctionDeclaration2.js]
-function () { }
+function default_1() { }
 exports.default = default_1;