I'm obtaining data.value which is a time in the format: hh:mm a - for example 12:30 am.

I also know:

1. the local timezone of the user (userTimeZone)
2. the timezone of the venue (venueTimeZone)

I need to convert the time selected by the user (data.value) to the correct date in the venueTimeZone. For example, if the user is in Americas/New York and they selected 1:30PM on the 20/05/2022, and the venue is in Americas/Los Angeles - the value I am interested in obtaining is 20/05/2022 10:30AM.

This is my attempt, however the timezone itself doesn't change - I think this is because when I create the userDateTime with moment I don't specify a time offset, but I'm not sure how to obtain the offset from userTimeZone, whilst accounting for DST.

            const userTimeZone = _.get(
                Intl.DateTimeFormat().resolvedOptions(),
                ['timeZone']
            );

            const venueDateStr = new Date().toLocaleString('en-US', {
                timeZone: venueTimeZone,
            });

            const Date = new Date(restaurantDateStr);
            const venueYear = venueDate.getFullYear();
            const venueMonth = `0${venueDate.getMonth()   1}`.slice(-2);
            const venueDateOfMonth = `0${venueDate.getDate()}`.slice(-2);

            const userDateTime = createDateAsUTC(
                moment(
                    `${venueDateOfMonth}/${venueMonth}/${venueYear} ${data.value}`,
                    'DD/MM/YYYY hh:mm a'
                ).toDate()
            ).toLocaleString('en-US', { timeZone: venueTimeZone });

EDIT - I do not have the city offset, I have the timezone name, therefore I cannot use any suggested answer which relies on city offset.

CodePudding user response：

Consider using Luxon - the successor to Moment. (See Moment's project status.)

// Parse your input string using the user's local time zone
// (this assumes the current local date)
const local = luxon.DateTime.fromFormat('1:30 pm', 'h:mm a');

// Convert to the desired time zone
const converted = local.setZone('America/Los_Angeles');

// Format the output as desired
const formatted = converted.toFormat('dd/MM/yyyy h:mm a').toLowerCase();

console.log(formatted);

<script src="https://cdnjs.cloudflare.com/ajax/libs/luxon/2.4.0/luxon.min.js"></script>

You could also do this without a library, however you may find that not all browsers will parse the input string, and your output format is up to the browser as well.

// Get the current local date as a string
const date = new Date().toLocaleDateString();

// Parse the date and time in the local time zone
// Warning: This is non-standard and may fail in some environments
const dt = new Date(date   ' 1:30 pm');

// Format the output, converting to the desired time zone
const result = dt.toLocaleString(undefined, { timeZone: 'America/Los_Angeles' });

console.log(result);

There are, of course, manual ways to parse and format dates (using regex, etc.) but I'll leave that up to you or another person to complete.