JavaScript / NodeJS-Mongo DB获取带偏移的日期（时区）

Question

We are loading Dates from a Mongo database. It seems that Mongo saves everything in UTC, but when JS creates Date objects (for display this dates) it adds/substracts the timezone offset. The result is, for example:

• If I save the date "2013-06-20 01:00:00"
• The date will be later auto-completed in a form as "2013-06-19 22:00:00" (Example for Argentina Time Zone UTC-03:00), and if the user saves that form without changing the date, the date will be saved with that wrong time.
• Worst that that, the next save will substracts 3 hours MORE, and so on!

As you see, I can get even different DAYS that the ones I wanted to save. I saw a few similar cases but nothing with this same technologies, I'm using Nodejs, MongoDB and Backbone. Right now I'm doing something like this:

    parse: function(response) {
       var dateStart = new Date(response.time.start);
       var offset = dateStart.getTimezoneOffset() * 60000;
       response.time.start = new Date(dateStart.valueOf() + offset);
       return response;
    }

But it's really ugly and I have to do it every time I instantiate a new Date()

Anybody know a nice way to fix this?

Answer 1

So sadly when you instantiate a Date object in a web browser, it will be in the browser's local time zone. Sometimes this helps, sometimes not. You can use moment.js moment.utc(myDate) to handle this and keep things in UTC. In general I highly recommend moment.js for your go-to Swiss Army knife of date related code.

Another approach would be to change your client to not submit fields to the server unless their value has truly changed.