Javascript date to C# via Ajax

Question

I have javascript date object which gives me a date string in this format, "Wed Dec 16 00:00:00 UTC-0400 2009".

I pass this via Ajax to the server (ASP.NET c#)

How can I convert, "Wed Dec 16 00:00:00 UTC-0400 2009" to a C# DateTime object. DateTime.Parse fails.

Answer 1

You can use DateTime.ParseExact which allows you to specify a format string to be used for parsing:

DateTime dt = DateTime.ParseExact("Wed Dec 16 00:00:00 UTC-0400 2009",
 "ddd MMM d HH:mm:ss UTCzzzzz yyyy",
 CultureInfo.InvariantCulture);

• ColacX: You may want to use DateTimeOffset instead.

Answer 2

The most reliable way would be to use milliseconds since the epoch. You can easily get this in JavaScript by calling Date.getTime(). Then, in C# you can convert it to a DateTime like this:

long msSinceEpoch = 1260402952906; // Value from Date.getTime() in JavaScript
return new DateTime(1970, 1, 1).AddTicks(msSinceEpoch * 10000);

You have to multiply by 10,000 to convert from milliseconds to "ticks", which are 100 nanoseconds.

• Joshua: I know this is an old, old answer but I do have a question. Is there any particular reason you add a new TimeSpan instead of calling DateTime's .AddMilliseconds method?
• EMP: No reason I can remember. I've edited the answer to use AddTicks now, which is probably marginally faster than AddMilliseconds (we're talking a few CPU cycles here).
• bopapa_1979: I got curious about why the "epoch" is 1970年01月01日. It turns out this is the "Unix epoch." I thought I'd share in case others are curious or confused: en.wikipedia.org/wiki/Unix_time
• bopapa_1979: Any reason not to just use DateTime.AddMilliseconds? return new DateTime(1970, 1, 1).AddMilliseconds(msSinceEpoch)
• Mahmood Dehghan Tazereh: Pay attention: JS Date.getTime returns the time in UTC. so if you want local time in C# you have to use ToLocalTime(): return new DateTime(1970, 1, 1).AddTicks(msSinceEpoch * 10000).ToLocalTime();

Answer 3

This may not be possible in your case, but I really recommend updating the JS code to pass dates/times in ISO 8601 format. http://en.wikipedia.org/wiki/ISO_8601

ISO 8601 is not only the formal standard, it's also easy to use and prevents a lot of timezone hassle!

To get 8601 datetime strings in Javascript:

var d = new Date();
var iso_time = d.toISOString(); //"2014-05-06T18:49:16.029Z"

To read 8601 datetime strings in C#:

DateTime d = DateTime.Parse(json_string);

• zomf: I see this as being the best approach because it's a single step and doesn't require jumping through any other hoops to handle the timezone or System.DateTime parsing.
• Ben Sewards: I'm using this approach to conform to momentjs

Answer 4

Just for posterity, to help future fellow Googlers, I'd like to expand on EMP's answer.

EMP's answer provides the time in UTC (if that's what you're looking for, use that).

To arrive at the client local time in C#:

In JavaScript:

 var now = new Date();
 var UTC = now.getTime();
 var localOffset = (-1) * now.getTimezoneOffset() * 60000;
 var currentTime = Math.round(new Date(UTC + localOffset).getTime()); 

In C#:

 DateTime currentTimeDotNet = new DateTime(1970, 1, 1).AddTicks(Convert.ToInt64(currentTime) * 10000);

Credit to this blog and EMP's answer, but took some trial and error on both ends to get it right, so just fyi for future folks.

• Dave Jellison: This is the most-correct answer that correctly handles time-zone adjustment.

Answer 5

To be honest I wouldn't try to parse that date string in C#, I'd personally try to create a more useful date structure from your javascript date object.

For instance you could use parse() in javascript which will return the ms representing the date object, which you can use DateTime.Parse() on to convert into a C# DateTime object.