## 计算当前毫秒数：

 const [start,setStart] = useState(new Date().getTime())useEffect(()=>{setInterval(()=>{setCurrMill(new Date().getTime()-start)},1)},[])

## 格式化毫秒 

 function formatMilliseconds(milliseconds) {const totalSeconds = Math.floor(milliseconds / 1000);const minutes = Math.floor(totalSeconds / 60);const seconds = totalSeconds % 60;const centiseconds = Math.floor((milliseconds % 1000) / 10);const formattedTime =(minutes < 10 ? '0' : '') +minutes +':' +(seconds < 10 ? '0' : '') +seconds +'.' +(centiseconds < 10 ? '0' : '') +centiseconds;return formattedTime;}

## 显示：