update docs

packages/artplayer/src/setting/playbackRate.js

@@ -1,3 +1,5 @@
+import { inverseClass, queryAll } from '../utils';
+
 export default function playbackRate(art) {
     const { i18n, icons } = art;
 
@@ -7,12 +9,23 @@ export default function playbackRate(art) {
         icon: icons.playbackRate,
         selector: [0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0].map((item) => {
             return {
+                value: item,
+                default: item === art.playbackRate,
                 html: item === 1.0 ? i18n.get('Normal') : item,
-                default: item === 1.0,
-                onSelect() {
-                    art.playbackRate = item;
-                },
             };
         }),
+        onSelect(item) {
+            art.playbackRate = item.value;
+        },
+        mounted: ($panel) => {
+            art.on('playbackRate', (value) => {
+                const $current = queryAll('.art-setting-item', $panel).find(
+                    (item) => Number(item.dataset.value) === value,
+                );
+                if ($current) {
+                    inverseClass($current, 'art-current');
+                }
+            });
+        },
     };
 }