js如何判斷video播放的視頻內(nèi)容是已經(jīng)緩存了的還是新請求的？比如clppr.js里面也沒有相關(guān)的狀態(tài)判斷。// You can either listen some events this wayvar player = new Clappr.Player({  events: {    onReady: function() { ... }, //Fired when the player is ready on startup    onResize: function() { ... },//Fired when player resizes    onPlay: function() { ... },//Fired when player starts to play    onPause: function() { ... },//Fired when player pauses    onStop: function() { ... },//Fired when player stops    onEnded: function() { ... },//Fired when player ends the video    onSeek: function() { ... },//Fired when player seeks the video    onError: function() { ... },//Fired when player receives an error    onTimeUpdate: function() { ... },//Fired when the time is updated on player    onVolumeUpdate: function() { ... },//Fired when player updates its volume  }})// or this wayplayer.on(Clappr.Events.PLAYER_PLAY, function() { ... })