在试验了所有Date.prototypes和Intl.DateTimeFormat
此函数帮助根据每个用户的时区进行逻辑，没有不可预见的服务器本地时间干扰
访问IANA time zone database以获取更多时区标识符，例如Asia/Shanghai、Asia/Kolkata、America/New_York。

function dateWithTZone (timezone,date){

    const options = {
      year: "numeric",
      month: "numeric",
      day: "numeric",
      hour: "numeric",
      minute: "numeric",
      second: "numeric",
      hour12: false,
      timeZone: timezone,
      timeZoneName: "longOffset",
    };
    const dateArray = new Intl.DateTimeFormat("en-US", options).formatToParts(date);
    const dateObj = dateArray.reduce((acc, cur) => ({...acc,[cur.type]: cur.value}),{});
    const {hourOffset,minuteOffset} = getOffset(dateObj.timeZoneName)
    return {...dateObj,hourOffset,minuteOffset}
}

function getOffset (timeZoneName){
    return {
      hourOffset: parseInt(
        timeZoneName.slice(3, 4) + timeZoneName.slice(4, 6)
      ),
      minuteOffset: parseInt(
        timeZoneName.slice(3, 4) + timeZoneName.slice(7, 9)
      ),
    };
}

从dateWithTZone()返回的month具有值1-12。通常Javascript月份值来自0-11。

// get the timezone from the user. here I use "Asia/Kolkata"
const {year,month,hourOffset,minuteOffset} = dateWithTZone("Asia/Kolkata",Date.now())
// I wanted to get user's current month end timestamp 
Date.UTC(year,month,1,-hourOffset,-minuteOffset)