处理切换页面之后，有效率数据的定时器没有销毁的问题

src/views/stationOperation/index.vue

@@ -185,6 +185,8 @@ export default {
       handler:function(val,oldVal) {
         if (val.name!=="station-operation") {
           this.$message.destroy()
+          clearInterval(this.timer);
+          this.timer = null
         }
       },
       deep:true,
@@ -233,7 +235,7 @@ export default {
     this.getStationTypeList()
     this.getStationTree()
   },
-  destroyed () {
+  beforeDestroy () {
     clearInterval(this.timer);
     this.timer = null
   },