orientationchange 事件

window.addEventListener('orientationchange',function(){
    //orientation 倾斜角度
    console.log(window.orientation);
    var orientation = "";
    switch(window.orientation){
      case 90: case -90:
            //当角度发生变化 横屏状态
           orientation = 'landscape';
      break;
      default:
          //默认竖屏状态
          orientation = 'portrait';
    }

},false);