react + ant Upload前端解析excel文件后时间解析为数字转化回日期格式

方法一：

（这种方法闰年转化后日期会有问题）

function formatDate(numb, format) {
        if (numb != undefined) {
  
            let time = new Date((numb - 1) * 24 * 3600000 + 1)
            time.setYear(time.getFullYear() - 70)
            let year = time.getFullYear() + ''
            let month = time.getMonth() + 1 + ''
            let date = time.getDate() + ''
            if (format && format.length === 1) {
                return year + format + month + format + date
            }
            return year + (month < 10 ? '0' + month : month) + (date < 10 ? '0' + date : date)
        } else {
            return undefined;
        }
    }

方法二：

（正确方法）

function formatDate(serial, format) {
        var utc_days = Math.floor(serial - 25569);
        var utc_value = utc_days * 86400;
        var date_info = new Date(utc_value * 1000);
        var fractional_day = serial - Math.floor(serial) + 0.0000001;
        var total_seconds = Math.floor(86400 * fractional_day);
        var seconds = total_seconds % 60;
        total_seconds -= seconds;
        var hours = Math.floor(total_seconds / (60 * 60));
        var minutes = Math.floor(total_seconds / 60) % 60;
 
        var daytime = new Date(date_info.getFullYear(), date_info.getMonth(), date_info.getDate(), hours, minutes, seconds);
        var returnDate = date_info.getFullYear();
        returnDate += format + (date_info.getMonth() < 9 ? '0' + (date_info.getMonth() + 1) : (date_info.getMonth() + 1));
        returnDate += format + (date_info.getDate() < 10 ? '0' + date_info.getDate() : date_info.getDate());
        returnDate += " " + (daytime.getHours() < 10 ? '0' + daytime.getHours() : daytime.getHours());
        returnDate += ":" + (daytime.getMinutes() < 10 ? '0' + daytime.getMinutes() : daytime.getMinutes());
        return returnDate;
 }　