From c17ec0ab23c62d54fc5a14cb8c3e900ece298735 Mon Sep 17 00:00:00 2001
From: Yoshiya Hinosawa <stibium121@gmail.com>
Date: Sat, 27 May 2017 04:44:34 +0900
Subject: [PATCH] Switch to rollup (#2037)

* chore: define run scripts, reduce grunt usage

* refactor(rollup): switch to rollup

* chore: fix node.js version on ci env
---
 .jshintrc            |   7 ++-
 .travis.yml          |   5 +--
 Gruntfile.coffee     |  80 +---------------------------------
 package.json         |   8 +++-
 src/api.axis.js      |   3 ++
 src/api.category.js  |   2 +
 src/api.chart.js     |   2 +
 src/api.color.js     |   2 +
 src/api.data.js      |   2 +
 src/api.flow.js      |   4 ++
 src/api.focus.js     |   3 ++
 src/api.grid.js      |   2 +
 src/api.group.js     |   3 ++
 src/api.legend.js    |   2 +
 src/api.load.js      |   2 +
 src/api.region.js    |   4 ++
 src/api.selection.js |   4 ++
 src/api.show.js      |   2 +
 src/api.tooltip.js   |   3 ++
 src/api.transform.js |   2 +
 src/api.x.js         |   2 +
 src/api.zoom.js      |   3 ++
 src/arc.js           |   4 ++
 src/axis.js          |   7 ++-
 src/c3.axis.js       |   2 +-
 src/cache.js         |   2 +
 src/category.js      |   2 +
 src/class-utils.js   | 101 +++++++++++++++++++++++++++++++++++++++++++
 src/class.js         | 100 +-----------------------------------------
 src/clip.js          |   2 +
 src/color.js         |   3 ++
 src/config.js        |   5 ++-
 src/core.js          |  38 +++++++++++++---
 src/data.convert.js  |   3 ++
 src/data.js          |   4 ++
 src/data.load.js     |   3 ++
 src/domain.js        |   3 ++
 src/drag.js          |   4 ++
 src/format.js        |   3 ++
 src/grid.js          |   4 ++
 src/head.js          |   4 --
 src/index.js         |  58 +++++++++++++++++++++++++
 src/interaction.js   |   3 ++
 src/legend.js        |   4 ++
 src/region.js        |   4 ++
 src/scale.js         |   2 +
 src/selection.js     |   3 ++
 src/shape.bar.js     |   4 ++
 src/shape.js         |   4 ++
 src/shape.line.js    |   4 ++
 src/size.js          |  10 +++--
 src/subchart.js      |   4 ++
 src/tail.js          |   9 ----
 src/text.js          |   3 ++
 src/title.js         |   3 ++
 src/tooltip.js       |   4 ++
 src/type.js          |   3 ++
 src/ua.js            |   2 +
 src/util.js          |  98 +++++++++++++++++++++--------------------
 src/zoom.js          |   4 ++
 60 files changed, 408 insertions(+), 259 deletions(-)
 create mode 100644 src/class-utils.js
 delete mode 100644 src/head.js
 create mode 100644 src/index.js
 delete mode 100644 src/tail.js

diff --git a/.jshintrc b/.jshintrc
index 164107c..f5504fa 100644
--- a/.jshintrc
+++ b/.jshintrc
@@ -1,7 +1,7 @@
 {
     "eqeqeq": true,
     "curly": true,
-    "strict": true,
+    "strict": false,
     "trailing": true,
     "white": true,
     "maxlen": 210,
@@ -24,7 +24,10 @@
         "beforeAll": false,
         "it": false,
         "expect": false,
-        "d3": false
+        "d3": false,
+        "module": false,
+        "require": false,
+        "define": false
     }
 
 }
diff --git a/.travis.yml b/.travis.yml
index 989225e..9642828 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,12 +1,11 @@
 language: node_js
+node_js:
+- 6
 
 before_install:
 - npm install -g grunt-cli
 - gem install sass
 
-script:
-- grunt
-
 after_success:
 - npm run codecov
 
diff --git a/Gruntfile.coffee b/Gruntfile.coffee
index f6dc622..745bf2a 100644
--- a/Gruntfile.coffee
+++ b/Gruntfile.coffee
@@ -1,84 +1,12 @@
 module.exports = (grunt) ->
-    require('load-grunt-tasks') grunt, pattern: ['grunt-contrib-*', 'grunt-sass', 'grunt-karma']
+    require('load-grunt-tasks') grunt, pattern: ['grunt-contrib-*', 'grunt-sass']
 
     grunt.initConfig
         watch:
-          concat:
-            tasks: 'concat'
-            files: ['src/*.js']
           sass:
             tasks: 'sass'
             files: ['src/scss/*.scss']
 
-        concat:
-          dist:
-            options:
-              process: (src, filepath) ->
-                if filepath != 'src/head.js' && filepath != 'src/tail.js'
-                  lines = []
-                  src.split('\n').forEach (line) ->
-                    lines.push( (if line.length > 0 then '    ' else '') + line)
-                  src = lines.join('\n')
-                return src
-            src: [
-              'src/head.js',
-              'src/core.js',
-              'src/config.js',
-              'src/scale.js',
-              'src/domain.js',
-              'src/data.js',
-              'src/data.convert.js',
-              'src/data.load.js',
-              'src/category.js',
-              'src/interaction.js',
-              'src/size.js',
-              'src/shape.js',
-              'src/shape.line.js',
-              'src/shape.bar.js',
-              'src/text.js',
-              'src/type.js',
-              'src/grid.js',
-              'src/tooltip.js',
-              'src/legend.js',
-              'src/title.js',
-              'src/axis.js',
-              'src/clip.js',
-              'src/arc.js',
-              'src/region.js',
-              'src/drag.js',
-              'src/selection.js',
-              'src/subchart.js',
-              'src/zoom.js',
-              'src/color.js',
-              'src/format.js',
-              'src/cache.js',
-              'src/class.js',
-              'src/util.js',
-              'src/api.focus.js',
-              'src/api.show.js',
-              'src/api.zoom.js',
-              'src/api.load.js',
-              'src/api.flow.js',
-              'src/api.selection.js',
-              'src/api.transform.js',
-              'src/api.group.js',
-              'src/api.grid.js',
-              'src/api.region.js',
-              'src/api.data.js',
-              'src/api.category.js',
-              'src/api.color.js',
-              'src/api.x.js',
-              'src/api.axis.js',
-              'src/api.legend.js',
-              'src/api.chart.js',
-              'src/api.tooltip.js',
-              'src/c3.axis.js',
-              'src/ua.js',
-              'src/polyfill.js',
-              'src/tail.js'
-            ]
-            dest: 'c3.js'
-
         jshint:
           c3: 'c3.js'
           spec: 'spec/*.js'
@@ -86,10 +14,6 @@ module.exports = (grunt) ->
             reporter: require('jshint-stylish')
             jshintrc: '.jshintrc'
 
-        karma:
-          unit:
-            configFile: 'karma.conf.js'
-
         uglify:
           c3:
             files:
@@ -108,7 +32,5 @@ module.exports = (grunt) ->
               'c3.css': 'src/scss/main.scss'
 
     grunt.registerTask 'lint', ['jshint']
-    grunt.registerTask 'test', ['karma']
     grunt.registerTask 'build', ['concat', 'sass']
     grunt.registerTask 'minify', ['cssmin', 'uglify']
-    grunt.registerTask 'default', ['lint', 'build', 'test', 'minify']
diff --git a/package.json b/package.json
index edaf70c..7c08c28 100644
--- a/package.json
+++ b/package.json
@@ -6,7 +6,10 @@
   "scripts": {
     "prepublish": "grunt",
     "lint": "grunt lint",
-    "test": "karma start karma.conf.js",
+    "build": "rollup -f umd --name c3 src/index.js > c3.js",
+    "minify": "grunt minify",
+    "test": "npm run build && npm run lint && karma start karma.conf.js",
+    "dist": "npm run build && npm run minify",
     "codecov": "cat coverage/*/lcov.info | codecov"
   },
   "repository": {
@@ -43,6 +46,7 @@
     "karma-phantomjs-launcher": "^0.2.1",
     "karma-spec-reporter": "0.0.20",
     "load-grunt-tasks": "~0.2.0",
-    "phantomjs": "^1.9.18"
+    "phantomjs": "^1.9.18",
+    "rollup": "^0.41.6"
   }
 }
diff --git a/src/api.axis.js b/src/api.axis.js
index 281a7bb..40c9bcc 100644
--- a/src/api.axis.js
+++ b/src/api.axis.js
@@ -1,3 +1,6 @@
+import { c3_chart_fn } from './core';
+import { isValue, isDefined } from './util';
+
 c3_chart_fn.axis = function () {};
 c3_chart_fn.axis.labels = function (labels) {
     var $$ = this.internal;
diff --git a/src/api.category.js b/src/api.category.js
index 1616c4a..a1c73cc 100644
--- a/src/api.category.js
+++ b/src/api.category.js
@@ -1,3 +1,5 @@
+import { c3_chart_fn } from './core';
+
 c3_chart_fn.category = function (i, category) {
     var $$ = this.internal, config = $$.config;
     if (arguments.length > 1) {
diff --git a/src/api.chart.js b/src/api.chart.js
index 0e4eacb..a06381a 100644
--- a/src/api.chart.js
+++ b/src/api.chart.js
@@ -1,3 +1,5 @@
+import { c3_chart_fn } from './core';
+
 c3_chart_fn.resize = function (size) {
     var $$ = this.internal, config = $$.config;
     config.size_width = size ? size.width : null;
diff --git a/src/api.color.js b/src/api.color.js
index 15aaa3e..680c4bb 100644
--- a/src/api.color.js
+++ b/src/api.color.js
@@ -1,3 +1,5 @@
+import { c3_chart_fn } from './core';
+
 // TODO: fix
 c3_chart_fn.color = function (id) {
     var $$ = this.internal;
diff --git a/src/api.data.js b/src/api.data.js
index be5b8f7..8793e64 100644
--- a/src/api.data.js
+++ b/src/api.data.js
@@ -1,3 +1,5 @@
+import { c3_chart_fn } from './core';
+
 c3_chart_fn.data = function (targetIds) {
     var targets = this.internal.data.targets;
     return typeof targetIds === 'undefined' ? targets : targets.filter(function (t) {
diff --git a/src/api.flow.js b/src/api.flow.js
index 2abad3e..a9431aa 100644
--- a/src/api.flow.js
+++ b/src/api.flow.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_fn, c3_chart_internal_fn } from './core';
+import { isValue, isDefined, diffDomain } from './util';
+
 c3_chart_fn.flow = function (args) {
     var $$ = this.internal,
         targets, data, notfoundIds = [], orgDataCount = $$.getMaxDataCount(),
diff --git a/src/api.focus.js b/src/api.focus.js
index 1a65bcc..bf00922 100644
--- a/src/api.focus.js
+++ b/src/api.focus.js
@@ -1,3 +1,6 @@
+import CLASS from './class';
+import { c3_chart_fn } from './core';
+
 c3_chart_fn.focus = function (targetIds) {
     var $$ = this.internal, candidates;
 
diff --git a/src/api.grid.js b/src/api.grid.js
index 038aa6b..1754188 100644
--- a/src/api.grid.js
+++ b/src/api.grid.js
@@ -1,3 +1,5 @@
+import { c3_chart_fn } from './core';
+
 c3_chart_fn.xgrids = function (grids) {
     var $$ = this.internal, config = $$.config;
     if (! grids) { return config.grid_x_lines; }
diff --git a/src/api.group.js b/src/api.group.js
index 47fedb4..e076b11 100644
--- a/src/api.group.js
+++ b/src/api.group.js
@@ -1,3 +1,6 @@
+import { c3_chart_fn } from './core';
+import { isUndefined } from './util';
+
 c3_chart_fn.groups = function (groups) {
     var $$ = this.internal, config = $$.config;
     if (isUndefined(groups)) { return config.data_groups; }
diff --git a/src/api.legend.js b/src/api.legend.js
index 182caa1..cc9ed75 100644
--- a/src/api.legend.js
+++ b/src/api.legend.js
@@ -1,3 +1,5 @@
+import { c3_chart_fn } from './core';
+
 c3_chart_fn.legend = function () {};
 c3_chart_fn.legend.show = function (targetIds) {
     var $$ = this.internal;
diff --git a/src/api.load.js b/src/api.load.js
index b2f0272..69be061 100644
--- a/src/api.load.js
+++ b/src/api.load.js
@@ -1,3 +1,5 @@
+import { c3_chart_fn } from './core';
+
 c3_chart_fn.load = function (args) {
     var $$ = this.internal, config = $$.config;
     // update xs if specified
diff --git a/src/api.region.js b/src/api.region.js
index b587b4f..14d5bce 100644
--- a/src/api.region.js
+++ b/src/api.region.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_fn } from './core';
+import { getOption } from './util';
+
 c3_chart_fn.regions = function (regions) {
     var $$ = this.internal, config = $$.config;
     if (!regions) { return config.regions; }
diff --git a/src/api.selection.js b/src/api.selection.js
index 02ad601..5b94b4b 100644
--- a/src/api.selection.js
+++ b/src/api.selection.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_fn } from './core';
+import { isDefined } from './util';
+
 c3_chart_fn.selected = function (targetId) {
     var $$ = this.internal, d3 = $$.d3;
     return d3.merge(
diff --git a/src/api.show.js b/src/api.show.js
index 08e99e1..5a34031 100644
--- a/src/api.show.js
+++ b/src/api.show.js
@@ -1,3 +1,5 @@
+import { c3_chart_fn } from './core';
+
 c3_chart_fn.show = function (targetIds, options) {
     var $$ = this.internal, targets;
 
diff --git a/src/api.tooltip.js b/src/api.tooltip.js
index 7c6dcb9..4f0b3cc 100644
--- a/src/api.tooltip.js
+++ b/src/api.tooltip.js
@@ -1,3 +1,6 @@
+import { c3_chart_fn } from './core';
+import { isValue } from './util';
+
 c3_chart_fn.tooltip = function () {};
 c3_chart_fn.tooltip.show = function (args) {
     var $$ = this.internal, index, mouse;
diff --git a/src/api.transform.js b/src/api.transform.js
index f04b505..b89c733 100644
--- a/src/api.transform.js
+++ b/src/api.transform.js
@@ -1,3 +1,5 @@
+import { c3_chart_fn, c3_chart_internal_fn } from './core';
+
 c3_chart_fn.transform = function (type, targetIds) {
     var $$ = this.internal,
         options = ['pie', 'donut'].indexOf(type) >= 0 ? {withTransform: true} : null;
diff --git a/src/api.x.js b/src/api.x.js
index 93d25d4..fedd5f2 100644
--- a/src/api.x.js
+++ b/src/api.x.js
@@ -1,3 +1,5 @@
+import { c3_chart_fn } from './core';
+
 c3_chart_fn.x = function (x) {
     var $$ = this.internal;
     if (arguments.length) {
diff --git a/src/api.zoom.js b/src/api.zoom.js
index 023ce68..cbcf6bf 100644
--- a/src/api.zoom.js
+++ b/src/api.zoom.js
@@ -1,3 +1,6 @@
+import { c3_chart_fn } from './core';
+import { isDefined } from './util';
+
 c3_chart_fn.zoom = function (domain) {
     var $$ = this.internal;
     if (domain) {
diff --git a/src/arc.js b/src/arc.js
index b94baab..c8c896b 100644
--- a/src/arc.js
+++ b/src/arc.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+import { isFunction } from './util';
+
 c3_chart_internal_fn.initPie = function () {
     var $$ = this, d3 = $$.d3, config = $$.config;
     $$.pie = d3.layout.pie().value(function (d) {
diff --git a/src/axis.js b/src/axis.js
index e3310b4..982af2d 100644
--- a/src/axis.js
+++ b/src/axis.js
@@ -1,4 +1,9 @@
-function Axis(owner) {
+import CLASS from './class';
+import { inherit, API } from './core'
+import { isValue, isFunction, isString, isEmpty } from './util';
+import c3_axis from './c3.axis'
+
+export default function Axis(owner) {
     API.call(this, owner);
 }
 
diff --git a/src/c3.axis.js b/src/c3.axis.js
index 6d4f7a3..0a702e1 100644
--- a/src/c3.axis.js
+++ b/src/c3.axis.js
@@ -3,7 +3,7 @@
 // 2. ceil values of translate/x/y to int for half pixel antialiasing
 // 3. multiline tick text
 var tickTextCharSize;
-function c3_axis(d3, params) {
+export default function c3_axis(d3, params) {
     var scale = d3.scale.linear(), orient = "bottom", innerTickSize = 6, outerTickSize, tickPadding = 3, tickValues = null, tickFormat, tickArguments;
 
     var tickOffset = 0, tickCulling = true, tickCentered;
diff --git a/src/cache.js b/src/cache.js
index 6566616..b2f05cc 100644
--- a/src/cache.js
+++ b/src/cache.js
@@ -1,3 +1,5 @@
+import { c3_chart_internal_fn } from './core';
+
 c3_chart_internal_fn.hasCaches = function (ids) {
     for (var i = 0; i < ids.length; i++) {
         if (! (ids[i] in this.cache)) { return false; }
diff --git a/src/category.js b/src/category.js
index 5143c6c..ea7fcba 100644
--- a/src/category.js
+++ b/src/category.js
@@ -1,3 +1,5 @@
+import { c3_chart_internal_fn } from './core';
+
 c3_chart_internal_fn.categoryName = function (i) {
     var config = this.config;
     return i < config.axis_x_categories.length ? config.axis_x_categories[i] : i;
diff --git a/src/class-utils.js b/src/class-utils.js
new file mode 100644
index 0000000..63d54e9
--- /dev/null
+++ b/src/class-utils.js
@@ -0,0 +1,101 @@
+import CLASS from './class'
+import { c3_chart_internal_fn } from './core';
+
+c3_chart_internal_fn.generateClass = function (prefix, targetId) {
+    return " " + prefix + " " + prefix + this.getTargetSelectorSuffix(targetId);
+};
+c3_chart_internal_fn.classText = function (d) {
+    return this.generateClass(CLASS.text, d.index);
+};
+c3_chart_internal_fn.classTexts = function (d) {
+    return this.generateClass(CLASS.texts, d.id);
+};
+c3_chart_internal_fn.classShape = function (d) {
+    return this.generateClass(CLASS.shape, d.index);
+};
+c3_chart_internal_fn.classShapes = function (d) {
+    return this.generateClass(CLASS.shapes, d.id);
+};
+c3_chart_internal_fn.classLine = function (d) {
+    return this.classShape(d) + this.generateClass(CLASS.line, d.id);
+};
+c3_chart_internal_fn.classLines = function (d) {
+    return this.classShapes(d) + this.generateClass(CLASS.lines, d.id);
+};
+c3_chart_internal_fn.classCircle = function (d) {
+    return this.classShape(d) + this.generateClass(CLASS.circle, d.index);
+};
+c3_chart_internal_fn.classCircles = function (d) {
+    return this.classShapes(d) + this.generateClass(CLASS.circles, d.id);
+};
+c3_chart_internal_fn.classBar = function (d) {
+    return this.classShape(d) + this.generateClass(CLASS.bar, d.index);
+};
+c3_chart_internal_fn.classBars = function (d) {
+    return this.classShapes(d) + this.generateClass(CLASS.bars, d.id);
+};
+c3_chart_internal_fn.classArc = function (d) {
+    return this.classShape(d.data) + this.generateClass(CLASS.arc, d.data.id);
+};
+c3_chart_internal_fn.classArcs = function (d) {
+    return this.classShapes(d.data) + this.generateClass(CLASS.arcs, d.data.id);
+};
+c3_chart_internal_fn.classArea = function (d) {
+    return this.classShape(d) + this.generateClass(CLASS.area, d.id);
+};
+c3_chart_internal_fn.classAreas = function (d) {
+    return this.classShapes(d) + this.generateClass(CLASS.areas, d.id);
+};
+c3_chart_internal_fn.classRegion = function (d, i) {
+    return this.generateClass(CLASS.region, i) + ' ' + ('class' in d ? d['class'] : '');
+};
+c3_chart_internal_fn.classEvent = function (d) {
+    return this.generateClass(CLASS.eventRect, d.index);
+};
+c3_chart_internal_fn.classTarget = function (id) {
+    var $$ = this;
+    var additionalClassSuffix = $$.config.data_classes[id], additionalClass = '';
+    if (additionalClassSuffix) {
+        additionalClass = ' ' + CLASS.target + '-' + additionalClassSuffix;
+    }
+    return $$.generateClass(CLASS.target, id) + additionalClass;
+};
+c3_chart_internal_fn.classFocus = function (d) {
+    return this.classFocused(d) + this.classDefocused(d);
+};
+c3_chart_internal_fn.classFocused = function (d) {
+    return ' ' + (this.focusedTargetIds.indexOf(d.id) >= 0 ? CLASS.focused : '');
+};
+c3_chart_internal_fn.classDefocused = function (d) {
+    return ' ' + (this.defocusedTargetIds.indexOf(d.id) >= 0 ? CLASS.defocused : '');
+};
+c3_chart_internal_fn.classChartText = function (d) {
+    return CLASS.chartText + this.classTarget(d.id);
+};
+c3_chart_internal_fn.classChartLine = function (d) {
+    return CLASS.chartLine + this.classTarget(d.id);
+};
+c3_chart_internal_fn.classChartBar = function (d) {
+    return CLASS.chartBar + this.classTarget(d.id);
+};
+c3_chart_internal_fn.classChartArc = function (d) {
+    return CLASS.chartArc + this.classTarget(d.data.id);
+};
+c3_chart_internal_fn.getTargetSelectorSuffix = function (targetId) {
+    return targetId || targetId === 0 ? ('-' + targetId).replace(/[\s?!@#$%^&*()_=+,.<>'":;\[\]\/|~`{}\\]/g, '-') : '';
+};
+c3_chart_internal_fn.selectorTarget = function (id, prefix) {
+    return (prefix || '') + '.' + CLASS.target + this.getTargetSelectorSuffix(id);
+};
+c3_chart_internal_fn.selectorTargets = function (ids, prefix) {
+    var $$ = this;
+    ids = ids || [];
+    return ids.length ? ids.map(function (id) { return $$.selectorTarget(id, prefix); }) : null;
+};
+c3_chart_internal_fn.selectorLegend = function (id) {
+    return '.' + CLASS.legendItem + this.getTargetSelectorSuffix(id);
+};
+c3_chart_internal_fn.selectorLegends = function (ids) {
+    var $$ = this;
+    return ids && ids.length ? ids.map(function (id) { return $$.selectorLegend(id); }) : null;
+};
diff --git a/src/class.js b/src/class.js
index 66171a7..fa18b13 100644
--- a/src/class.js
+++ b/src/class.js
@@ -1,4 +1,4 @@
-var CLASS = c3_chart_internal_fn.CLASS = {
+export default {
     target: 'c3-target',
     chart: 'c3-chart',
     chartLine: 'c3-chart-line',
@@ -75,101 +75,3 @@ var CLASS = c3_chart_internal_fn.CLASS = {
     SELECTED: '_selected_',
     INCLUDED: '_included_'
 };
-c3_chart_internal_fn.generateClass = function (prefix, targetId) {
-    return " " + prefix + " " + prefix + this.getTargetSelectorSuffix(targetId);
-};
-c3_chart_internal_fn.classText = function (d) {
-    return this.generateClass(CLASS.text, d.index);
-};
-c3_chart_internal_fn.classTexts = function (d) {
-    return this.generateClass(CLASS.texts, d.id);
-};
-c3_chart_internal_fn.classShape = function (d) {
-    return this.generateClass(CLASS.shape, d.index);
-};
-c3_chart_internal_fn.classShapes = function (d) {
-    return this.generateClass(CLASS.shapes, d.id);
-};
-c3_chart_internal_fn.classLine = function (d) {
-    return this.classShape(d) + this.generateClass(CLASS.line, d.id);
-};
-c3_chart_internal_fn.classLines = function (d) {
-    return this.classShapes(d) + this.generateClass(CLASS.lines, d.id);
-};
-c3_chart_internal_fn.classCircle = function (d) {
-    return this.classShape(d) + this.generateClass(CLASS.circle, d.index);
-};
-c3_chart_internal_fn.classCircles = function (d) {
-    return this.classShapes(d) + this.generateClass(CLASS.circles, d.id);
-};
-c3_chart_internal_fn.classBar = function (d) {
-    return this.classShape(d) + this.generateClass(CLASS.bar, d.index);
-};
-c3_chart_internal_fn.classBars = function (d) {
-    return this.classShapes(d) + this.generateClass(CLASS.bars, d.id);
-};
-c3_chart_internal_fn.classArc = function (d) {
-    return this.classShape(d.data) + this.generateClass(CLASS.arc, d.data.id);
-};
-c3_chart_internal_fn.classArcs = function (d) {
-    return this.classShapes(d.data) + this.generateClass(CLASS.arcs, d.data.id);
-};
-c3_chart_internal_fn.classArea = function (d) {
-    return this.classShape(d) + this.generateClass(CLASS.area, d.id);
-};
-c3_chart_internal_fn.classAreas = function (d) {
-    return this.classShapes(d) + this.generateClass(CLASS.areas, d.id);
-};
-c3_chart_internal_fn.classRegion = function (d, i) {
-    return this.generateClass(CLASS.region, i) + ' ' + ('class' in d ? d['class'] : '');
-};
-c3_chart_internal_fn.classEvent = function (d) {
-    return this.generateClass(CLASS.eventRect, d.index);
-};
-c3_chart_internal_fn.classTarget = function (id) {
-    var $$ = this;
-    var additionalClassSuffix = $$.config.data_classes[id], additionalClass = '';
-    if (additionalClassSuffix) {
-        additionalClass = ' ' + CLASS.target + '-' + additionalClassSuffix;
-    }
-    return $$.generateClass(CLASS.target, id) + additionalClass;
-};
-c3_chart_internal_fn.classFocus = function (d) {
-    return this.classFocused(d) + this.classDefocused(d);
-};
-c3_chart_internal_fn.classFocused = function (d) {
-    return ' ' + (this.focusedTargetIds.indexOf(d.id) >= 0 ? CLASS.focused : '');
-};
-c3_chart_internal_fn.classDefocused = function (d) {
-    return ' ' + (this.defocusedTargetIds.indexOf(d.id) >= 0 ? CLASS.defocused : '');
-};
-c3_chart_internal_fn.classChartText = function (d) {
-    return CLASS.chartText + this.classTarget(d.id);
-};
-c3_chart_internal_fn.classChartLine = function (d) {
-    return CLASS.chartLine + this.classTarget(d.id);
-};
-c3_chart_internal_fn.classChartBar = function (d) {
-    return CLASS.chartBar + this.classTarget(d.id);
-};
-c3_chart_internal_fn.classChartArc = function (d) {
-    return CLASS.chartArc + this.classTarget(d.data.id);
-};
-c3_chart_internal_fn.getTargetSelectorSuffix = function (targetId) {
-    return targetId || targetId === 0 ? ('-' + targetId).replace(/[\s?!@#$%^&*()_=+,.<>'":;\[\]\/|~`{}\\]/g, '-') : '';
-};
-c3_chart_internal_fn.selectorTarget = function (id, prefix) {
-    return (prefix || '') + '.' + CLASS.target + this.getTargetSelectorSuffix(id);
-};
-c3_chart_internal_fn.selectorTargets = function (ids, prefix) {
-    var $$ = this;
-    ids = ids || [];
-    return ids.length ? ids.map(function (id) { return $$.selectorTarget(id, prefix); }) : null;
-};
-c3_chart_internal_fn.selectorLegend = function (id) {
-    return '.' + CLASS.legendItem + this.getTargetSelectorSuffix(id);
-};
-c3_chart_internal_fn.selectorLegends = function (ids) {
-    var $$ = this;
-    return ids && ids.length ? ids.map(function (id) { return $$.selectorLegend(id); }) : null;
-};
diff --git a/src/clip.js b/src/clip.js
index 322dbb5..bb6029d 100644
--- a/src/clip.js
+++ b/src/clip.js
@@ -1,3 +1,5 @@
+import { c3_chart_internal_fn } from './core';
+
 c3_chart_internal_fn.getClipPath = function (id) {
     var isIE9 = window.navigator.appVersion.toLowerCase().indexOf("msie 9.") >= 0;
     return "url(" + (isIE9 ? "" : document.URL.split('#')[0]) + "#" + id + ")";
diff --git a/src/color.js b/src/color.js
index da1888e..4585d85 100644
--- a/src/color.js
+++ b/src/color.js
@@ -1,3 +1,6 @@
+import { c3_chart_internal_fn } from './core';
+import { notEmpty } from './util';
+
 c3_chart_internal_fn.generateColor = function () {
     var $$ = this, config = $$.config, d3 = $$.d3,
         colors = config.data_colors,
diff --git a/src/config.js b/src/config.js
index c127be5..54d5b18 100644
--- a/src/config.js
+++ b/src/config.js
@@ -1,3 +1,6 @@
+import { c3_chart_internal_fn } from './core';
+import { isDefined } from './util';
+
 c3_chart_internal_fn.getDefaultConfig = function () {
     var config = {
         bindto: '#chart',
@@ -121,7 +124,7 @@ c3_chart_internal_fn.getDefaultConfig = function () {
         axis_y_label: {},
         axis_y_tick_format: undefined,
         axis_y_tick_outer: true,
-        axis_y_tick_values: null,        
+        axis_y_tick_values: null,
         axis_y_tick_rotate: 0,
         axis_y_tick_count: undefined,
         axis_y_tick_time_value: undefined,
diff --git a/src/core.js b/src/core.js
index 7a933d5..94ac711 100644
--- a/src/core.js
+++ b/src/core.js
@@ -1,14 +1,20 @@
-var c3 = { version: "0.4.11" };
+import Axis from './axis';
+import CLASS from './class';
+import { isValue, isFunction, isString, isUndefined, isDefined, ceil10, asHalfPixel, diffDomain, isEmpty, notEmpty, getOption, hasValue, sanitise, getPathBox } from './util';
 
-var c3_chart_fn,
-    c3_chart_internal_fn,
-    c3_chart_internal_axis_fn;
+export var c3 = { version: "0.4.11" };
 
-function API(owner) {
+export var c3_chart_fn;
+export var c3_chart_internal_fn;
+export var c3_chart_internal_axis_fn;
+
+var d3 = window.d3 ? window.d3 : typeof require !== 'undefined' ? require("d3") : undefined;
+
+export function API(owner) {
     this.owner = owner;
 }
 
-function inherit(base, derived) {
+export function inherit(base, derived) {
 
     if (Object.create) {
         derived.prototype = Object.create(base.prototype);
@@ -44,7 +50,7 @@ function Chart(config) {
 
 function ChartInternal(api) {
     var $$ = this;
-    $$.d3 = window.d3 ? window.d3 : typeof require !== 'undefined' ? require("d3") : undefined;
+    $$.d3 = d3
     $$.api = api;
     $$.config = $$.getDefaultConfig();
     $$.data = {};
@@ -1059,3 +1065,21 @@ c3_chart_internal_fn.isTabVisible = function () {
 
     return document[hidden] ? false : true;
 };
+
+c3_chart_internal_fn.isValue = isValue;
+c3_chart_internal_fn.isFunction = isFunction;
+c3_chart_internal_fn.isString = isString;
+c3_chart_internal_fn.isUndefined = isUndefined;
+c3_chart_internal_fn.isDefined = isDefined;
+c3_chart_internal_fn.ceil10 = ceil10;
+c3_chart_internal_fn.asHalfPixel = asHalfPixel;
+c3_chart_internal_fn.diffDomain = diffDomain;
+c3_chart_internal_fn.isEmpty = isEmpty;
+c3_chart_internal_fn.notEmpty = notEmpty;
+c3_chart_internal_fn.notEmpty = notEmpty;
+c3_chart_internal_fn.getOption = getOption;
+c3_chart_internal_fn.hasValue = hasValue;
+c3_chart_internal_fn.sanitise = sanitise;
+c3_chart_internal_fn.getPathBox = getPathBox;
+c3_chart_internal_fn.CLASS = CLASS;
+
diff --git a/src/data.convert.js b/src/data.convert.js
index 8c523f5..00853f6 100644
--- a/src/data.convert.js
+++ b/src/data.convert.js
@@ -1,3 +1,6 @@
+import { c3_chart_internal_fn } from './core';
+import { isValue, isUndefined, isDefined, notEmpty } from './util';
+
 c3_chart_internal_fn.convertUrlToData = function (url, mimeType, headers, keys, done) {
     var $$ = this, type = mimeType ? mimeType : 'csv';
     var req = $$.d3.xhr(url);
diff --git a/src/data.js b/src/data.js
index 531ab69..90cb36b 100644
--- a/src/data.js
+++ b/src/data.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+import { isValue, isFunction, notEmpty, hasValue } from './util';
+
 c3_chart_internal_fn.isX = function (key) {
     var $$ = this, config = $$.config;
     return (config.data_x && key === config.data_x) || (notEmpty(config.data_xs) && hasValue(config.data_xs, key));
diff --git a/src/data.load.js b/src/data.load.js
index 3b5bf72..376d7e9 100644
--- a/src/data.load.js
+++ b/src/data.load.js
@@ -1,3 +1,6 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+
 c3_chart_internal_fn.load = function (targets, args) {
     var $$ = this;
     if (targets) {
diff --git a/src/domain.js b/src/domain.js
index 770c63f..5439b57 100644
--- a/src/domain.js
+++ b/src/domain.js
@@ -1,3 +1,6 @@
+import { c3_chart_internal_fn } from './core';
+import { isValue, isDefined, diffDomain, notEmpty } from './util';
+
 c3_chart_internal_fn.getYDomainMin = function (targets) {
     var $$ = this, config = $$.config,
         ids = $$.mapToIds(targets), ys = $$.getValuesAsIdKeyed(targets),
diff --git a/src/drag.js b/src/drag.js
index 56ab070..dce7bcf 100644
--- a/src/drag.js
+++ b/src/drag.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+import { getPathBox } from './util';
+
 c3_chart_internal_fn.drag = function (mouse) {
     var $$ = this, config = $$.config, main = $$.main, d3 = $$.d3;
     var sx, sy, mx, my, minX, maxX, minY, maxY;
diff --git a/src/format.js b/src/format.js
index aa72780..6fe60e5 100644
--- a/src/format.js
+++ b/src/format.js
@@ -1,3 +1,6 @@
+import { c3_chart_internal_fn } from './core';
+import { isValue } from './util';
+
 c3_chart_internal_fn.getYFormat = function (forArc) {
     var $$ = this,
         formatForY = forArc && !$$.hasType('gauge') ? $$.defaultArcValueFormat : $$.yFormat,
diff --git a/src/grid.js b/src/grid.js
index 9a06432..ddf417e 100644
--- a/src/grid.js
+++ b/src/grid.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+import { isValue } from './util';
+
 c3_chart_internal_fn.initGrid = function () {
     var $$ = this, config = $$.config, d3 = $$.d3;
     $$.grid = $$.main.append('g')
diff --git a/src/head.js b/src/head.js
deleted file mode 100644
index d77cbd0..0000000
--- a/src/head.js
+++ /dev/null
@@ -1,4 +0,0 @@
-(function (window) {
-    'use strict';
-
-    /*global define, module, exports, require */
diff --git a/src/index.js b/src/index.js
new file mode 100644
index 0000000..dd9cbeb
--- /dev/null
+++ b/src/index.js
@@ -0,0 +1,58 @@
+import { c3 } from './core'
+
+import './polyfill';
+
+import './api.axis';
+import './api.category';
+import './api.chart';
+import './api.color';
+import './api.data';
+import './api.flow';
+import './api.focus';
+import './api.grid';
+import './api.group';
+import './api.legend';
+import './api.load';
+import './api.region';
+import './api.selection';
+import './api.show';
+import './api.tooltip';
+import './api.transform';
+import './api.x';
+import './api.zoom';
+import './arc';
+import './axis';
+import './c3.axis';
+import './cache';
+import './category';
+import './class';
+import './class-utils';
+import './clip';
+import './color';
+import './config';
+import './data.convert';
+import './data';
+import './data.load';
+import './domain';
+import './drag';
+import './format';
+import './grid';
+import './interaction';
+import './legend';
+import './region';
+import './scale';
+import './selection';
+import './shape.bar';
+import './shape';
+import './shape.line';
+import './size';
+import './subchart';
+import './text';
+import './title';
+import './tooltip';
+import './type';
+import './ua';
+import './util';
+import './zoom';
+
+export default c3
diff --git a/src/interaction.js b/src/interaction.js
index c6203d9..a51f6de 100644
--- a/src/interaction.js
+++ b/src/interaction.js
@@ -1,3 +1,6 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+
 c3_chart_internal_fn.initEventRect = function () {
     var $$ = this;
     $$.main.select('.' + CLASS.chart).append("g")
diff --git a/src/legend.js b/src/legend.js
index 158b503..355a8e0 100644
--- a/src/legend.js
+++ b/src/legend.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+import { isDefined, isEmpty, getOption } from './util';
+
 c3_chart_internal_fn.initLegend = function () {
     var $$ = this;
     $$.legendItemTextBox = {};
diff --git a/src/region.js b/src/region.js
index 0439a80..83ca16e 100644
--- a/src/region.js
+++ b/src/region.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+import { isValue } from './util';
+
 c3_chart_internal_fn.initRegion = function () {
     var $$ = this;
     $$.region = $$.main.append('g')
diff --git a/src/scale.js b/src/scale.js
index 6c4c045..85fa792 100644
--- a/src/scale.js
+++ b/src/scale.js
@@ -1,3 +1,5 @@
+import { c3_chart_internal_fn } from './core';
+
 c3_chart_internal_fn.getScale = function (min, max, forTimeseries) {
     return (forTimeseries ? this.d3.time.scale() : this.d3.scale.linear()).range([min, max]);
 };
diff --git a/src/selection.js b/src/selection.js
index b71d286..c1d0551 100644
--- a/src/selection.js
+++ b/src/selection.js
@@ -1,3 +1,6 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+
 c3_chart_internal_fn.selectPoint = function (target, d, i) {
     var $$ = this, config = $$.config,
         cx = (config.axis_rotated ? $$.circleY : $$.circleX).bind($$),
diff --git a/src/shape.bar.js b/src/shape.bar.js
index 514b7f0..de11922 100644
--- a/src/shape.bar.js
+++ b/src/shape.bar.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+import { isValue } from './util';
+
 c3_chart_internal_fn.initBar = function () {
     var $$ = this;
     $$.main.select('.' + CLASS.chart).append("g")
diff --git a/src/shape.js b/src/shape.js
index 38afae1..930b422 100644
--- a/src/shape.js
+++ b/src/shape.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+import { isUndefined } from './util';
+
 c3_chart_internal_fn.getShapeIndices = function (typeFilter) {
     var $$ = this, config = $$.config,
         indices = {}, i = 0, j, k;
diff --git a/src/shape.line.js b/src/shape.line.js
index e9dcb8c..421d7f9 100644
--- a/src/shape.line.js
+++ b/src/shape.line.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+import { isValue, isFunction, isUndefined, isDefined } from './util';
+
 c3_chart_internal_fn.initLine = function () {
     var $$ = this;
     $$.main.select('.' + CLASS.chart).append("g")
diff --git a/src/size.js b/src/size.js
index 445d11d..c4892ca 100644
--- a/src/size.js
+++ b/src/size.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+import { isValue, ceil10 } from './util';
+
 c3_chart_internal_fn.getCurrentWidth = function () {
     var $$ = this, config = $$.config;
     return config.size_width ? config.size_width : $$.getParentWidth();
@@ -5,7 +9,7 @@ c3_chart_internal_fn.getCurrentWidth = function () {
 c3_chart_internal_fn.getCurrentHeight = function () {
     var $$ = this, config = $$.config,
         h = config.size_height ? config.size_height : $$.getParentHeight();
-    return h > 0 ? h : 320 / ($$.hasType('gauge') && !config.gauge_fullCircle ? 2 : 1); 
+    return h > 0 ? h : 320 / ($$.hasType('gauge') && !config.gauge_fullCircle ? 2 : 1);
 };
 c3_chart_internal_fn.getCurrentPaddingTop = function () {
     var $$ = this,
@@ -95,8 +99,8 @@ c3_chart_internal_fn.getHorizontalAxisHeight = function (axisId) {
     var $$ = this, config = $$.config, h = 30;
     if (axisId === 'x' && !config.axis_x_show) { return 8; }
     if (axisId === 'x' && config.axis_x_height) { return config.axis_x_height; }
-    if (axisId === 'y' && !config.axis_y_show) { 
-        return config.legend_show && !$$.isLegendRight && !$$.isLegendInset ? 10 : 1; 
+    if (axisId === 'y' && !config.axis_y_show) {
+        return config.legend_show && !$$.isLegendRight && !$$.isLegendInset ? 10 : 1;
     }
     if (axisId === 'y2' && !config.axis_y2_show) { return $$.rotated_padding_top; }
     // Calculate x axis height when tick rotated
diff --git a/src/subchart.js b/src/subchart.js
index 47017a5..a4dacf7 100644
--- a/src/subchart.js
+++ b/src/subchart.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+import { isFunction } from './util';
+
 c3_chart_internal_fn.initBrush = function () {
     var $$ = this, d3 = $$.d3;
     $$.brush = d3.svg.brush().on("brush", function () { $$.redrawForBrush(); });
diff --git a/src/tail.js b/src/tail.js
deleted file mode 100644
index 541ccf3..0000000
--- a/src/tail.js
+++ /dev/null
@@ -1,9 +0,0 @@
-    if (typeof define === 'function' && define.amd) {
-        define("c3", ["d3"], function () { return c3; });
-    } else if ('undefined' !== typeof exports && 'undefined' !== typeof module) {
-        module.exports = c3;
-    } else {
-        window.c3 = c3;
-    }
-
-})(window);
diff --git a/src/text.js b/src/text.js
index 9327037..25f55fa 100644
--- a/src/text.js
+++ b/src/text.js
@@ -1,3 +1,6 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+
 c3_chart_internal_fn.initText = function () {
     var $$ = this;
     $$.main.select('.' + CLASS.chart).append("g")
diff --git a/src/title.js b/src/title.js
index a58b68e..6c198c5 100644
--- a/src/title.js
+++ b/src/title.js
@@ -1,3 +1,6 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+
 c3_chart_internal_fn.initTitle = function () {
     var $$ = this;
     $$.title = $$.svg.append("text")
diff --git a/src/tooltip.js b/src/tooltip.js
index 1ceafe4..148e80b 100644
--- a/src/tooltip.js
+++ b/src/tooltip.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+import { isValue, isString, sanitise } from './util';
+
 c3_chart_internal_fn.initTooltip = function () {
     var $$ = this, config = $$.config, i;
     $$.tooltip = $$.selectChart
diff --git a/src/type.js b/src/type.js
index 6497280..620f7ef 100644
--- a/src/type.js
+++ b/src/type.js
@@ -1,3 +1,6 @@
+import { c3_chart_internal_fn } from './core';
+import { isString } from './util';
+
 c3_chart_internal_fn.setTargetType = function (targetIds, type) {
     var $$ = this, config = $$.config;
     $$.mapToTargetIds(targetIds).forEach(function (id) {
diff --git a/src/ua.js b/src/ua.js
index 17fcde5..71dacaa 100644
--- a/src/ua.js
+++ b/src/ua.js
@@ -1,3 +1,5 @@
+import { c3_chart_internal_fn } from './core';
+
 c3_chart_internal_fn.isSafari = function () {
     var ua = window.navigator.userAgent;
     return ua.indexOf('Safari') >= 0 && ua.indexOf('Chrome') < 0;
diff --git a/src/util.js b/src/util.js
index 1365ab3..63304bf 100644
--- a/src/util.js
+++ b/src/util.js
@@ -1,49 +1,51 @@
-var isValue = c3_chart_internal_fn.isValue = function (v) {
+import { c3_chart_internal_fn } from './core';
+
+export var isValue = function (v) {
     return v || v === 0;
-},
-    isFunction = c3_chart_internal_fn.isFunction = function (o) {
-        return typeof o === 'function';
-    },
-    isString = c3_chart_internal_fn.isString = function (o) {
-        return typeof o === 'string';
-    },
-    isUndefined = c3_chart_internal_fn.isUndefined = function (v) {
-        return typeof v === 'undefined';
-    },
-    isDefined = c3_chart_internal_fn.isDefined = function (v) {
-        return typeof v !== 'undefined';
-    },
-    ceil10 = c3_chart_internal_fn.ceil10 = function (v) {
-        return Math.ceil(v / 10) * 10;
-    },
-    asHalfPixel = c3_chart_internal_fn.asHalfPixel = function (n) {
-        return Math.ceil(n) + 0.5;
-    },
-    diffDomain = c3_chart_internal_fn.diffDomain = function (d) {
-        return d[1] - d[0];
-    },
-    isEmpty = c3_chart_internal_fn.isEmpty = function (o) {
-        return typeof o === 'undefined' || o === null || (isString(o) && o.length === 0) || (typeof o === 'object' && Object.keys(o).length === 0);
-    },
-    notEmpty = c3_chart_internal_fn.notEmpty = function (o) {
-        return !c3_chart_internal_fn.isEmpty(o);
-    },
-    getOption = c3_chart_internal_fn.getOption = function (options, key, defaultValue) {
-        return isDefined(options[key]) ? options[key] : defaultValue;
-    },
-    hasValue = c3_chart_internal_fn.hasValue = function (dict, value) {
-        var found = false;
-        Object.keys(dict).forEach(function (key) {
-            if (dict[key] === value) { found = true; }
-        });
-        return found;
-    },
-    sanitise = c3_chart_internal_fn.sanitise = function (str) {
-        return typeof str === 'string' ? str.replace(/</g, '&lt;').replace(/>/g, '&gt;') : str;
-    },
-    getPathBox = c3_chart_internal_fn.getPathBox = function (path) {
-        var box = path.getBoundingClientRect(),
-            items = [path.pathSegList.getItem(0), path.pathSegList.getItem(1)],
-            minX = items[0].x, minY = Math.min(items[0].y, items[1].y);
-        return {x: minX, y: minY, width: box.width, height: box.height};
-    };
+};
+export var isFunction = function (o) {
+    return typeof o === 'function';
+};
+export var isString = function (o) {
+    return typeof o === 'string';
+};
+export var isUndefined = function (v) {
+return typeof v === 'undefined';
+};
+export var isDefined = function (v) {
+    return typeof v !== 'undefined';
+};
+export var ceil10 = function (v) {
+    return Math.ceil(v / 10) * 10;
+};
+export var asHalfPixel = function (n) {
+    return Math.ceil(n) + 0.5;
+};
+export var diffDomain = function (d) {
+    return d[1] - d[0];
+};
+export var isEmpty = function (o) {
+    return typeof o === 'undefined' || o === null || (isString(o) && o.length === 0) || (typeof o === 'object' && Object.keys(o).length === 0);
+};
+export var notEmpty = function (o) {
+    return !c3_chart_internal_fn.isEmpty(o);
+};
+export var getOption = function (options, key, defaultValue) {
+    return isDefined(options[key]) ? options[key] : defaultValue;
+};
+export var hasValue = function (dict, value) {
+    var found = false;
+    Object.keys(dict).forEach(function (key) {
+        if (dict[key] === value) { found = true; }
+    });
+    return found;
+};
+export var sanitise = function (str) {
+    return typeof str === 'string' ? str.replace(/</g, '&lt;').replace(/>/g, '&gt;') : str;
+};
+export var getPathBox = function (path) {
+    var box = path.getBoundingClientRect(),
+        items = [path.pathSegList.getItem(0), path.pathSegList.getItem(1)],
+        minX = items[0].x, minY = Math.min(items[0].y, items[1].y);
+    return {x: minX, y: minY, width: box.width, height: box.height};
+};
diff --git a/src/zoom.js b/src/zoom.js
index c11dd8b..fea6bda 100644
--- a/src/zoom.js
+++ b/src/zoom.js
@@ -1,3 +1,7 @@
+import CLASS from './class';
+import { c3_chart_internal_fn } from './core';
+import { diffDomain } from './util';
+
 c3_chart_internal_fn.initZoom = function () {
     var $$ = this, d3 = $$.d3, config = $$.config, startEvent;