Change data api interface

c3.js

@@ -5967,14 +5967,13 @@
         return config.regions;
     };
 
-    c3_chart_fn.data = function () {};
-    c3_chart_fn.data.get = function (targetId) {
-        var target = this.data.getAsTarget(targetId);
-        return isDefined(target) ? target.values.map(function (d) { return d.value; }) : undefined;
-    };
-    c3_chart_fn.data.getAsTarget = function (targetId) {
-        var targets = this.data.targets.filter(function (t) { return t.id === targetId; });
-        return targets.length > 0 ? targets[0] : undefined;
+    c3_chart_fn.data = function (targetId) {
+        var targets = this.internal.data.targets.filter(function (t) { return t.id === targetId; });
+        return targets.length > 0 ? targets[0] : null;
+    };
+    c3_chart_fn.data.values = function (targetId) {
+        var target = this.data(targetId);
+        return target ? target.values.map(function (d) { return d.value; }) : null;
     };
     c3_chart_fn.data.names = function (names) {
         var $$ = this.internal, config = $$.config;

src/api.data.js

@@ -1,11 +1,10 @@
-c3_chart_fn.data = function () {};
-c3_chart_fn.data.get = function (targetId) {
-    var target = this.data.getAsTarget(targetId);
-    return isDefined(target) ? target.values.map(function (d) { return d.value; }) : undefined;
+c3_chart_fn.data = function (targetId) {
+    var targets = this.internal.data.targets.filter(function (t) { return t.id === targetId; });
+    return targets.length > 0 ? targets[0] : null;
 };
-c3_chart_fn.data.getAsTarget = function (targetId) {
-    var targets = this.data.targets.filter(function (t) { return t.id === targetId; });
-    return targets.length > 0 ? targets[0] : undefined;
+c3_chart_fn.data.values = function (targetId) {
+    var target = this.data(targetId);
+    return target ? target.values.map(function (d) { return d.value; }) : null;
 };
 c3_chart_fn.data.names = function (names) {
     var $$ = this.internal, config = $$.config;