怎么判断手机屏幕是横屏的,还是竖屏的

window.onload = function(){
            //横竖屏
            function doOnOrientationChange(){
                switch(window.orientation){
                    case 90:
                        transverse();
                        break;
                    case -90:
                        transverse();
                        break;
                    default:
                        vertical();
                        break;
                }
            }
            window.addEventListener("onorientationchange" in window ? "orientationchange" : "resize", doOnOrientationChange, false);
            doOnOrientationChange();
            function transverse(){
                jQuery("#loading").hide();

            }
            function vertical(){
                jQuery("#loading").show();
            }
        }