The slider.value from `touchstart` event is the previous one before the slider change, after the first `input` fires, the slider.value will be the up-to-date and sync with the ui.

We want to let the new volume be to affected immediately, so we should use the latest value form the slider, which is the one from the first `input` event, or we will need to wait for the first `setVolume()` from `setInterval()` to set the newest volume.