allow export default non-functions mapping to module.exports in common module formatter - fixes #356

lib/6to5/transformation/modules/_default.js

@@ -126,7 +126,7 @@ DefaultFormatter.prototype._pushStatement = function (ref, nodes) {
 
 DefaultFormatter.prototype._hoistExport = function (declar, assign, priority) {
   if (t.isFunctionDeclaration(declar)) {
-    assign._blockHoist = priority || 1;
+    assign._blockHoist = priority || 2;
   }
 
   return assign;

lib/6to5/transformation/modules/common.js

@@ -57,6 +57,7 @@ CommonJSFormatter.prototype.importDeclaration = function (node, nodes) {
 CommonJSFormatter.prototype.exportDeclaration = function (node, nodes) {
   if (node.default) {
     var declar = node.declaration;
+    var assign;
 
     // module.exports = VALUE;
     var templateName = "exports-default-module";
@@ -64,15 +65,29 @@ CommonJSFormatter.prototype.exportDeclaration = function (node, nodes) {
     // exports = module.exports = VALUE;
     if (this.hasNonDefaultExports) templateName = "exports-default-module-override";
 
-    var assign = util.template(templateName, {
-      VALUE: this._pushStatement(declar, nodes)
-    }, true);
+    if (t.isFunction(declar) || !this.hasNonDefaultExports) {
+      assign = util.template(templateName, {
+        VALUE: this._pushStatement(declar, nodes)
+      }, true);
 
-    // hoist to the top if this default is a function
-    nodes.push(this._hoistExport(declar, assign, 2));
-  } else {
-    DefaultFormatter.prototype.exportDeclaration.apply(this, arguments);
+      // hoist to the top if this default is a function
+      nodes.push(this._hoistExport(declar, assign, 3));
+      return;
+    } else {
+      // this export isn't a function so we can't hoist it to the top so we need to set it
+      // at the very end of the file with something like:
+      //
+      //   module.exports = Object.assign(exports["default"], exports)
+      //
+
+      assign = util.template("common-export-default-assign", true);
+      assign._blockHoist = 0;
+
+      nodes.push(assign);
+    }
   }
+
+  DefaultFormatter.prototype.exportDeclaration.apply(this, arguments);
 };
 
 CommonJSFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {

lib/6to5/transformation/templates/common-export-default-assign.js

@@ -0,0 +1 @@
+module.exports = Object.assign(exports["default"], exports);

lib/6to5/transformation/transformers/_block-hoist.js

@@ -1,17 +1,27 @@
 var _ = require("lodash");
 
+// Priority:
+//
+//  - 0 We want this to be at the **very** bottom
+//  - 1 Default node position
+//  - 2 Priority over normal nodes
+//  - 3 We want this to be at the **very** top
+
 exports.BlockStatement =
 exports.Program = {
   exit: function (node) {
     var hasChange = false;
     for (var i in node.body) {
       var bodyNode = node.body[i];
-      if (bodyNode && bodyNode._blockHoist) hasChange = true;
+      if (bodyNode && bodyNode._blockHoist != null) hasChange = true;
     }
     if (!hasChange) return;
 
     var nodePriorities = _.groupBy(node.body, function (bodyNode) {
-      return bodyNode._blockHoist || 0;
+      var priority = bodyNode._blockHoist;
+      if (priority == null) priority = 1;
+      if (priority === true) priority = 2;
+      return priority;
     });
 
     node.body = _.flatten(_.values(nodePriorities).reverse());

test/fixtures/transformation/es6-modules-common/exports-default-non-function/actual.js

@@ -0,0 +1,3 @@
+export default new Cachier()
+
+export function Cachier(databaseName) {}

test/fixtures/transformation/es6-modules-common/exports-default-non-function/expected.js

@@ -0,0 +1,6 @@
+"use strict";
+
+exports.Cachier = Cachier;
+exports["default"] = new Cachier();
+function Cachier(databaseName) {}
+module.exports = Object.assign(exports["default"], exports);

test/fixtures/transformation/es6-modules-common/overview/actual.js

@@ -8,5 +8,3 @@ import {foo as bar} from "foo";
 
 export {test};
 export var test = 5;
-
-export default test;

test/fixtures/transformation/es6-modules-common/overview/expected.js

@@ -18,5 +18,3 @@ var bar = require("foo").bar;
 var bar = require("foo").foo;
 exports.test = test;
 var test = exports.test = 5;
-
-exports = module.exports = test;