fix:修复父页面向子页面传值错误的问题；

pages-a/a-test/a-test.vue

@@ -34,8 +34,9 @@
         uni.navigateTo({
           url:'/pages-b/b-test/b-test'
         });
+        let that = this;
         setTimeout(()=>{
-          uni.$emit('transA',{msg:'A->B'});
+          uni.$emit('transA',{msg:that.msg});
         },100);
       },
     }