diff --git a/src/components/ECharts.vue b/src/components/ECharts.vue
index 1e761d6..6b11f2e 100644
--- a/src/components/ECharts.vue
+++ b/src/components/ECharts.vue
@@ -64,7 +64,7 @@ export default {
   },
   data () {
     return {
-      chart: null,
+      // deleted to make this.chart not reactive
       lastArea: 0
     }
   },