How do you convert a JavaScript date to UTC?

Question

Suppose a user of your website enters a date range.

2009-1-1 to 2009-1-3 

You need to send this date to a server for some processing, but the server expects all dates and times to be in UTC.

Now suppose the user is in Alaska or Hawaii or Fiji. Since they are in a timezone quite different from UTC, the date range needs to be converted to something like this:

2009-1-1T8:00:00 to 2009-1-4T7:59:59 

Using the JavaScript Date object, how would you convert the first "localized" date range into something the server will understand?

Answer 1

The toISOString() method returns a string in simplified extended ISO format (ISO 8601), which is always 24 or 27 characters long (YYYY-MM-DDTHH:mm:ss.sssZ or ±YYYYYY-MM-DDTHH:mm:ss.sssZ, respectively). The timezone is always zero UTC offset, as denoted by the suffix "Z".

Source: MDN web docs

The format you need is created with the .toISOString() method. For older browsers (ie8 and under), which don't natively support this method, the shim can be found here:

This will give you the ability to do what you need:

var isoDateString = new Date().toISOString(); console.log(isoDateString);

For Timezone work, moment.js and moment.js timezone are really invaluable tools...especially for navigating timezones between client and server javascript.

Answer 2

Simple and stupid

var date = new Date();  var now_utc =  Date.UTC(date.getUTCFullYear(), date.getUTCMonth(), date.getUTCDate(),  date.getUTCHours(), date.getUTCMinutes(), date.getUTCSeconds());   return new Date(now_utc);