add some polyfill to demo

docs/assets/js/common.js

@@ -108,7 +108,7 @@
     }
 
     function runExample(name) {
-        fetch(`./assets/example/${name}.js`)
+        fetch('./assets/example/' + name + '.js')
             .then(function (response) {
                 return response.text();
             })
@@ -150,9 +150,9 @@
         var code = mirror.getValue();
         eval(code);
         initArt(Artplayer.instances[0]);
-        console.debug(`Artplayer@${Artplayer.version}`);
-        console.debug(`Env@${Artplayer.env}`);
-        console.debug(`Build@${formatDate(Artplayer.build)}`);
+        console.debug('Artplayer@' + Artplayer.version);
+        console.debug('Env@' + Artplayer.env);
+        console.debug('Build@' + formatDate(Artplayer.build));
     }
 
     function initApp() {

docs/index.html

@@ -67,13 +67,17 @@
     <div class="popups">
         <div class="popinner"></div>
     </div>
+    <script src="./assets/js/vconsole.min.js"></script>
     <script src="./assets/js/core.js"></script>
+    <script src="./assets/js/fetch.polyfill.js"></script>
+    <script src="./assets/js/encoding-indexes.js"></script>
+    <script src="./assets/js/encoding.js"></script>
     <script src="./assets/js/codemirror.js"></script>
     <script src="./assets/js/javascript.js"></script>
     <script src="./assets/js/console.js"></script>
     <script src="./uncompiled/artplayer.js"></script>
-    <script src="./assets/js/common.js"></script>
     <script>
+        // var vConsole = new VConsole();
         var isLocalhost = Boolean(
             window.location.hostname === 'localhost' ||
             window.location.hostname === '[::1]' ||
@@ -91,6 +95,7 @@
             }
         })();
     </script>
+    <script src="./assets/js/common.js"></script>
 </body>
 
 </html>

packages/artplayer/src/subtitle.js

@@ -109,6 +109,7 @@ export default class Subtitle extends Component {
             proxy(this.textTrack, 'cuechange', this.update.bind(this));
         }
 
+        errorHandle(window.fetch, 'fetch not support');
         return fetch(url)
             .then((response) => response.arrayBuffer())
             .then((buffer) => {