need to reuse pScanner

Author: Keillion

1.hello-world/5.read-video-vue/src/components/ImgDecode.vue

@@ -14,7 +14,7 @@ export default {
   methods: {
     async decodeImg(e) {
       try {
-        const reader = await (this.pReader = BarcodeReader.createInstance());
+        const reader = await (this.pReader = this.pReader || BarcodeReader.createInstance());
         let results = await reader.decode(e.target.files[0]);
         for(let result of results){
           alert(result.barcodeText);

1.hello-world/5.read-video-vue/src/components/VideoDecode.vue

@@ -36,7 +36,7 @@ export default {
   },
   async mounted() {
     try {
-      const scanner = await (this.pScanner = BarcodeScanner.createInstance());
+      const scanner = await (this.pScanner = this.pScanner || BarcodeScanner.createInstance());
       await scanner.setUIElement(this.$el);
       scanner.onFrameRead = (results) => {
         for (let result of results) {