[demo] - udpate comment

examples/pureJS/js/index.js

@@ -208,6 +208,7 @@ window.onload = function () {
         const streams = isLocalStream ? this.state.localStreams : this.state.remoteStreams;
         const idx = streams.findIndex(item => item.sid === previous.sid);
         if (idx >= 0) {
+          // 更新流的信息
           const oldStream = streams.splice(idx, 1, current)[0];
           this.unrenderStream(oldStream);
           streams.push(current);

examples/react/src/pages/room/index.jsx

@@ -84,6 +84,7 @@ export default class Room extends Component {
       const streams = isLocalStream ? this.state.localStreams : this.state.remoteStreams;
       const idx = streams.findIndex(item => item.sid === previous.sid);
       if (idx >= 0) {
+        // 更新流的信息
         streams.splice(idx, 1, current);
       }
       if (isLocalStream) {

examples/vue/src/pages/Room.vue

@@ -109,6 +109,7 @@ export default {
       const streams = isLocalStream ? this.localStreams : this.remoteStreams;
       const idx = streams.findIndex(item => item.sid === previous.sid);
       if (idx >= 0) {
+        // 更新流的信息
         streams.splice(idx, 1, current);
       }
     });