pixijs 显示帧速率

    var g_Time=0;
        app.ticker.add((delta) => {
             var timeNow = (new Date()).getTime(); 
            var timeDiff = timeNow - g_Time; 
                g_Time = timeNow; 
                var zhenlv=1000/timeDiff;
              
            console.log(zhenlv);

        });