Update 12.read-video-es6.html

Author: Cube-J

1.hello-world/12.read-video-es6.html

@@ -30,7 +30,7 @@ <h1 style="font-size: 1.5em;">Hello World for ES6</h1>
         BarcodeReader.engineResourcePath = "https://cdn.jsdelivr.net/npm/dynamsoft-javascript-barcode@9.0.1/dist/";
 
         let pScanner = null;
-        window.onload = async () => {
+        (async () => {
             try {
                 const scanner = await (pScanner = pScanner || BarcodeScanner.createInstance());
                 /* 
@@ -57,8 +57,8 @@ <h1 style="font-size: 1.5em;">Hello World for ES6</h1>
                 alert(ex.message);
                 throw ex;
             }
-        };
+        })();
     </script>
 </body>
 
-</html>
+</html>