refactor: add localStorage supporting

src/js/plyr.js

@@ -2001,6 +2001,9 @@
             plyr.media.playbackRate = speed;
 
             _updateSpeedupTooltip(speed);
+
+            // Save speed to localStorage
+            _updateStorage({speed: speed});
         }
 
         // Seek to time
@@ -2570,6 +2573,16 @@
             }
         }
 
+        // Set playback speed
+        function _setSpeedup(speed) {
+            // Load speed from storage or default value
+            if (_is.undefined(speed)) {
+                speed = plyr.storage.speed || config.defaultSpeed;
+            }
+
+            _speedup(speed);
+        }
+
         // Update hover tooltip for playback speed changed
         function _updateSpeedupTooltip(speed) {
             if (!isNaN(speed)) {
@@ -3438,6 +3451,9 @@
             _setVolume();
             _updateVolume();
 
+            // Set playback speed
+            _setSpeedup();
+
             // Reset time display
             _timeUpdate();