--- a/static/candolint.js	Fri Oct 06 16:06:44 2017 +0800
+++ b/static/candolint.js	Fri Oct 06 16:22:57 2017 +0800
@@ -70,13 +70,16 @@
         y1.rangeRound([height, 0]);
         y2.rangeRound([height, 0]);
 
-        cg.append('line')
-            .attr('stroke', '#000')
-            .attr('stroke-dasharray', '5,2')
-            .attr('x1', x(data.current) + 0.5)
-            .attr('y1', 0)
-            .attr('x2', x(data.current) + 0.5)
-            .attr('y2', height);
+        var cx = x(data.current) + 0.5;
+        if (!isNaN(cx)) {
+            cg.append('line')
+                .attr('stroke', '#000')
+                .attr('stroke-dasharray', '5,2')
+                .attr('x1', cx)
+                .attr('y1', 0)
+                .attr('x2', cx)
+                .attr('y2', height);
+        }
 
         var hover = cg.append('line')
             .attr('opacity', 0)