Moving Rollup config out of Gruntfile.

.babelrc

@@ -0,0 +1,13 @@
+{
+  "presets": [
+    [
+      "es2015",
+      {
+        "modules": false
+      }
+    ]
+  ],
+  "plugins": [
+    "external-helpers"
+  ]
+}

Gruntfile.coffee

@@ -1,24 +1,11 @@
 module.exports = (grunt) ->
-    require('load-grunt-tasks') grunt, pattern: ['grunt-contrib-*', 'grunt-sass', 'grunt-karma', 'grunt-rollup']
+    require('load-grunt-tasks') grunt, pattern: ['grunt-contrib-*', 'grunt-sass', 'grunt-karma']
 
 
 
 
 
     grunt.initConfig
-        rollup: 
-          options: 
-            external: ['d3']
-            format: "umd"
-            moduleName: "c3"
-            globals:
-              d3: 'd3'
-            
-          files: 
-            src: 'es6_modules/rollup.entry.js'
-            dest: 'c3.es6.js'
-          
-      
         watch:
           concat:
             tasks: 'concat'
@@ -236,4 +223,4 @@ module.exports = (grunt) ->
     grunt.registerTask 'build', ['concat:dist', 'sass']
     grunt.registerTask 'minify', ['cssmin', 'uglify']
     grunt.registerTask 'default', ['lint', 'build', 'test', 'minify']
-    grunt.registerTask 'build_rollup', ['concat:axis', 'concat:chart', 'concat:chartinternal','rollup']
+    grunt.registerTask 'build_modules', ['concat:axis', 'concat:chart', 'concat:chartinternal']

package.json

@@ -6,7 +6,8 @@
   "scripts": {
     "lint": "grunt lint",
     "test": "karma start karma.conf.js",
-    "codecov": "cat coverage/*/lcov.info | codecov"
+    "codecov": "cat coverage/*/lcov.info | codecov",
+    "build": "rollup -c"
   },
   "repository": {
     "type": "git",
@@ -25,6 +26,8 @@
     "d3": "^3.5.17"
   },
   "devDependencies": {
+    "babel-plugin-external-helpers": "^6.8.0",
+    "babel-preset-es2015": "^6.14.0",
     "codecov.io": "^0.1.6",
     "grunt": "^1.0.1",
     "grunt-contrib-concat": "^1.0.1",
@@ -33,7 +36,6 @@
     "grunt-contrib-uglify": "^1.0.1",
     "grunt-contrib-watch": "^1.0.0",
     "grunt-karma": "^2.0.0",
-    "grunt-rollup": "^0.7.1",
     "grunt-sass": "^1.2.0",
     "jasmine-core": "^2.4.1",
     "jshint-stylish": "^2.2.0",
@@ -43,6 +45,8 @@
     "karma-phantomjs-launcher": "^1.0.1",
     "karma-spec-reporter": "0.0.26",
     "load-grunt-tasks": "^3.5.0",
-    "phantomjs-prebuilt": "^2.1.7"
+    "phantomjs-prebuilt": "^2.1.7",
+    "rollup": "^0.35.10",
+    "rollup-plugin-babel": "^2.6.1"
   }
 }

rollup.config.js

@@ -0,0 +1,21 @@
+/**
+ * Rollup Config
+ */
+
+import babel from 'rollup-plugin-babel';
+
+export default {
+    entry: 'es6_modules/rollup.entry.js',
+    format: 'umd',
+    moduleName: 'c3',
+    external: ['d3'],
+    globals: {
+        d3: 'd3',
+    },
+    plugins: [
+        babel({
+            exclude: 'node_modules/**'
+        })
+    ],
+    dest: 'c3.js'
+};