simplify amd module formatter

MODULES.md

@@ -66,8 +66,7 @@ export function bar() {
 **Out**
 
 ```javascript
-define(["foo"], function (_foo) {
+define(["exports", "foo"], function (exports, _foo) {
-  var exports = {};
   exports.bar = bar;
 
   var foo = _foo.default;
@@ -75,8 +74,6 @@ define(["foo"], function (_foo) {
   function bar() {
     return foo("foobar");
   }
-
-  return exports;
 });
 ```
 

lib/6to5/modules/amd.js

@@ -18,22 +18,18 @@ AMDFormatter.prototype.transform = function (ast) {
 
   // build an array of module names
 
-  var names = [];
+  var names = [b.literal("exports")];
   _.each(this.ids, function (id, name) {
     names.push(b.literal(name));
   });
   names = b.arrayExpression(names);
 
-  // add exports
-
-  body.unshift(b.variableDeclaration("var", [
-    b.variableDeclarator(b.identifier("exports"), b.objectExpression([]))
-  ]));
-  body.push(b.returnStatement(b.identifier("exports")));
-
   // build up define container
 
-  var container = b.functionExpression(null, _.values(this.ids), b.blockStatement(body));
+  var params = _.values(this.ids);
+  params.unshift(b.identifier("exports"));
+
+  var container = b.functionExpression(null, params, b.blockStatement(body));
   var call = b.callExpression(b.identifier("define"), [names, container]);
 
   program.body = [b.expressionStatement(call)];

test/fixtures/syntax/modules-amd/exports-default/expected.js

@@ -1,8 +1,6 @@
 "use strict";
 
-define([], function () {
+define(["exports"], function (exports) {
-  var exports = {};
-
   exports.default = 42;
   exports.default = {};
   exports.default = [];
@@ -20,6 +18,4 @@ define([], function () {
     var foo = function foo() {};
     return foo;
   }();
-
-  return exports;
 });

test/fixtures/syntax/modules-amd/exports-from/expected.js

@@ -1,8 +1,6 @@
 "use strict";
 
-define(["foo"], function (_foo) {
+define(["exports", "foo"], function (exports, _foo) {
-  var exports = {};
-
   (function(obj) {
     for (var i in obj) {
       exports[i] = obj[i];
@@ -16,6 +14,4 @@ define(["foo"], function (_foo) {
   exports.default = _foo.foo;
   exports.default = _foo.foo;
   exports.bar = _foo.bar;
-
-  return exports;
 });

test/fixtures/syntax/modules-amd/exports-named/expected.js

@@ -1,8 +1,6 @@
 "use strict";
 
-define([], function () {
+define(["exports"], function (exports) {
-  var exports = {};
-
   exports.foo = foo;
   exports.foo = foo;
   exports.bar = bar;
@@ -10,6 +8,4 @@ define([], function () {
   exports.default = foo;
   exports.default = foo;
   exports.bar = bar;
-
-  return exports;
 });

test/fixtures/syntax/modules-amd/exports-variable/expected.js

@@ -1,8 +1,6 @@
 "use strict";
 
-define([], function () {
+define(["exports"], function (exports) {
-  var exports = {};
-
   exports.foo7 = foo7;
   var foo = 1;
   exports.foo = foo;
@@ -24,6 +22,4 @@ define([], function () {
   }();
 
   exports.foo8 = foo8;
-
-  return exports;
 });

test/fixtures/syntax/modules-amd/hoist-function-exports/expected.js

@@ -1,8 +1,6 @@
 "use strict";
 
-define(["./evens"], function (_evens) {
+define(["exports", "./evens"], function (exports, _evens) {
-  var exports = {};
-
   exports.nextOdd = nextOdd;
   var isEven = _evens.isEven;
 
@@ -17,6 +15,4 @@ define(["./evens"], function (_evens) {
   }(isEven);
 
   exports.isOdd = isOdd;
-
-  return exports;
 });

test/fixtures/syntax/modules-amd/imports-default/expected.js

@@ -1,10 +1,6 @@
 "use strict";
 
-define(["foo"], function (_foo) {
+define(["exports", "foo"], function (exports, _foo) {
-  var exports = {};
-
   var foo = _foo.default;
   var foo = _foo.default;
-
-  return exports;
 });

test/fixtures/syntax/modules-amd/imports-glob/expected.js

@@ -1,9 +1,5 @@
 "use strict";
 
-define(["foo"], function (_foo) {
+define(["exports", "foo"], function (exports, _foo) {
-  var exports = {};
-
   var foo = _foo;
-
-  return exports;
 });

test/fixtures/syntax/modules-amd/imports-mixing/expected.js

@@ -1,10 +1,6 @@
 "use strict";
 
-define(["foo"], function (_foo) {
+define(["exports", "foo"], function (exports, _foo) {
-  var exports = {};
-
   var foo = _foo.default;
   var xyz = _foo.baz;
-
-  return exports;
 });

test/fixtures/syntax/modules-amd/imports-named/expected.js

@@ -1,14 +1,10 @@
 "use strict";
 
-define(["foo"], function (_foo) {
+define(["exports", "foo"], function (exports, _foo) {
-  var exports = {};
-
   var bar = _foo.bar;
   var bar = _foo.bar;
   var baz = _foo.baz;
   var baz = _foo.bar;
   var baz = _foo.bar;
   var xyz = _foo.xyz;
-
-  return exports;
 });

test/fixtures/syntax/modules-amd/imports/expected.js

@@ -1,7 +1,5 @@
 "use strict";
 
-define(["foo", "foo-bar", "./directory/foo-bar"], function (_foo, _fooBar, _directoryFooBar) {
+define(["exports", "foo", "foo-bar", "./directory/foo-bar"], function (exports, _foo, _fooBar, _directoryFooBar) {
-  var exports = {};
 
-  return exports;
 });

test/fixtures/syntax/modules-amd/overview/expected.js

@@ -1,8 +1,6 @@
 "use strict";
 
-define(["foo", "foo-bar", "./directory/foo-bar"], function (_foo, _fooBar, _directoryFooBar) {
+define(["exports", "foo", "foo-bar", "./directory/foo-bar"], function (exports, _foo, _fooBar, _directoryFooBar) {
-  var exports = {};
-
   var foo = _foo.default;
   var foo = _foo;
   var bar = _foo.bar;
@@ -11,6 +9,4 @@ define(["foo", "foo-bar", "./directory/foo-bar"], function (_foo, _fooBar, _dire
   var test = 5;
   exports.test = test;
   exports.default = test;
-
-  return exports;
 });