如何以时间戳格式将此 DatePicker 保存到 firestore?

How can I save this DatePicker to firestore in a timestamp format?

我想将它保存在 firestore 中,但目前它是这样保存的 1/20/2021

const [seconDate, setSecondDate] = useState(new Date());

<MuiPickersUtilsProvider utils={DateFnsUtils}>
                          <DatePicker
                            format="MM/dd/yyyy"
                            value={secondDate}
                            onChange={setSeconDate}
                            fullWidth
                            id="date-picker-inline"
               
                          />
                        </MuiPickersUtilsProvider>

提交到 firebase 时,处理日期 like so.

const dateArray = seconDate.split('/');
const dateFormatted = new Date(dateArray[2], dateArray[1] - 1, dateArray[0]);
const timestamp = dateFormatted.getTime();
console.log(timestamp);