change undefined to null

Author: tangjinzhou

demo/src/App.vue

@@ -47,19 +47,10 @@ export default {
     }
   },
   mounted() {
-    console.log(this.$refs.spanList)
-    console.log(this.img === this.$refs.img)
-    console.log(this.helloWorld === this.$refs.helloWorld)
-    console.log(this.button === this.$refs.button)
-    console.log(this.scrollbar === this.$refs.scrollbar)
-    console.log(this.functional === this.$refs.functional, this.$refs.functional, this.functional)
+    this.refsLog()
   },
   updated() {
-    console.log(this.img === this.$refs.img)
-    console.log(this.helloWorld === this.$refs.helloWorld)
-    console.log(this.button === this.$refs.button)
-    console.log(this.scrollbar === this.$refs.scrollbar)
-    console.log(this.functional === this.$refs.functional)
+    this.refsLog()
   },
   methods: {
   	onEnter() {
@@ -70,6 +61,17 @@ export default {
     },
     updateMsg(){
       this.msg = Date.now()
+    },
+    refsLog(){
+      console.log(this.$refs.spanList)
+      console.log(this.img === this.$refs.img)
+      console.log(this.helloWorld === this.$refs.helloWorld)
+      if(this.helloWorld !== this.$refs.helloWorld) {
+        console.log(this.helloWorld, this.$refs.helloWorld)
+      }
+      console.log(this.button === this.$refs.button)
+      console.log(this.scrollbar === this.$refs.scrollbar)
+      console.log(this.functional === this.$refs.functional, this.$refs.functional, this.functional)
     }
   }
 }

demo/src/components/HelloWorld.vue

@@ -2,13 +2,21 @@
   <div class="hello">
     <h1>{{ msg }}</h1>
     <h2>Hello World</h2>
+    <p>innerState: {{innerState}}</p>
+    <a-button @click="++innerState">change innerState</a-button>
   </div>
 </template>
 
 <script>
 export default {
   name: 'HelloWorld',
   props: ['msg'],
+  data(){
+    return {
+      innerState: 1 
+    }
+  },
+
 }
 </script>
 

index.js

@@ -9,7 +9,7 @@ export default {
       },
       unbind: function (el, binding, vnode) {
         if(!el.parentNode && !el.parentElement) {
-          binding.value(undefined, vnode.key)
+          binding.value(null, vnode.key)
         }
       },
     })

package.json

@@ -1,6 +1,6 @@
 {
     "name": "vue-ref",
-    "version": "1.0.0",
+    "version": "1.0.1",
     "title": "Vue Ref",
     "description": "use the callback to get a reference like react",
     "keywords": [