从开始dateTime（ISO格式）和持续时间（hh：mm格式）计算结束日期时间（ISO格式）

Question

Let,

startDateTime => 2019-05-18T11:40:00-07:00

timeZone => -07:00

duration => 23:10

durationHrs => 23

durationMin => 10

endDateTime => ?? (be in same format as of startDateTime )

So far, I tried as below :

const endMs = (+new Date(startDateTime)) + (((durationHrs)*60*60+(durationMin)*60)*1000);
const endDateTime = `${new Date(endMs).toISOString().split('.')[0]}${timeZone}`;
console.log(endDateTime);

Please, take care of time zone . Thnaks in advance !!

Answer 1

There is no way to automatically convert the UTC date into some random timezone. It will work if the user lives in that specific timezone. Anyway, you can use simple math to fix this problem.

Calculate the timeline different in the millisecond

const timeZone= `-07:00` 

const timezoneDiff = timeZone[0]==='-' ?  (timezone.split(':')[0]*60*60*1000 - timeZone.split(':')[1]*60*1000) : (timeZone.split(':')[0]*60*60*1000 + timeZone.split(':')[1]*60*1000)

Add the difference to the standard UNIX timestamp

const endDateTime = `${new Date( endMs1+ (timeZoneDiff)).toISOString().split('.')[0]}${timeZone}`;

Or else use some NPM module like moment or moment-timezone

Answer 2

I tried again and finally got a solution using javascript and momentjs by playing with milliseconds.

const st = '2019-05-18T11:40:00-07:00';

const tz = '-07:00'

const dur = '23:10';

const hr = 23;

const mn = 10;


const convert = (num) => num < 10 ? "0" + num : num;
const hrs = hr * 60 * 60 * 1000;
const mins = mn * 60 * 1000;
const getms = new Date(`${st.split('-')[0]}:00`).getTime();
const totalMs = getms + hrs + mins;

const year = new Date(totalMs).getFullYear();
const month = convert(new Date(totalMs).getMonth()+1);
const date = convert(new Date(totalMs).getDate());

const getHrs = convert(new Date(totalMs).getHours());
const getMin = convert(new Date(totalMs).getMinutes());

const getendTime = `${year}-${month}-${date} ${getHrs}:${getMin}:00`;


const momentend = moment.tz(getendTime, moment.tz.guess()).clone().tz(this.$data.selectedZone.split('$')[1]).format();

console.log(momentend);