Fix tickInterval when transition

c3.js

@@ -6621,7 +6621,6 @@
         var scale = d3.scale.linear(), orient = "bottom", innerTickSize = 6, outerTickSize, tickPadding = 3, tickValues = null, tickFormat, tickArguments;
 
         var tickOffset = 0, tickCulling = true, tickCentered;
-        var axis_g;
 
         params = params || {};
         outerTickSize = params.withOuterTick ? 6 : 0;
@@ -6688,9 +6687,9 @@
             return size;
         }
         function axis(g) {
-            axis_g = g;
             g.each(function () {
-                var g = d3.select(this);
+                var g = axis.g = d3.select(this);
+
                 var scale0 = this.__chart__ || scale, scale1 = this.__chart__ = copyScale();
 
                 var ticks = tickValues ? tickValues : generateTicks(scale1),
@@ -6882,8 +6881,8 @@
                 interval = tickOffset * 2;
             }
             else {
-                length = axis_g.select('path.domain').node().getTotalLength() - outerTickSize * 2;
-                interval = length / axis_g.selectAll('line').size();
+                length = axis.g.select('path.domain').node().getTotalLength() - outerTickSize * 2;
+                interval = length / axis.g.selectAll('line').size();
             }
             return interval;
         };

src/c3.axis.js

@@ -7,7 +7,6 @@ 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;
-    var axis_g;
 
     params = params || {};
     outerTickSize = params.withOuterTick ? 6 : 0;
@@ -74,9 +73,9 @@ function c3_axis(d3, params) {
         return size;
     }
     function axis(g) {
-        axis_g = g;
         g.each(function () {
-            var g = d3.select(this);
+            var g = axis.g = d3.select(this);
+
             var scale0 = this.__chart__ || scale, scale1 = this.__chart__ = copyScale();
 
             var ticks = tickValues ? tickValues : generateTicks(scale1),
@@ -268,8 +267,8 @@ function c3_axis(d3, params) {
             interval = tickOffset * 2;
         }
         else {
-            length = axis_g.select('path.domain').node().getTotalLength() - outerTickSize * 2;
-            interval = length / axis_g.selectAll('line').size();
+            length = axis.g.select('path.domain').node().getTotalLength() - outerTickSize * 2;
+            interval = length / axis.g.selectAll('line').size();
         }
         return interval;
     };