Convert C# DateTime to Javascript Date

Question

I have a function in Javascript that receives a C# DateTime from MVC. If the date is null it should return "-", if it's a valid date it should return the formated date.

IMPORTANT: It's not possible to send the date in another format from C#.

Javascript:

function CheckDate(date) {

  if (date == "Mon Jan 01 0001 00:00:00 GMT+0000 (GMT Daylight Time)")
    return "-";
  else {
    var dat = new Date(date);
    return dat.getFullYear() + dat.getMonth() + dat.getDay();
  }

Is there a better way to compare if the date is the C# New DateTime?

And how do I parse and return the date in "yyyy/MM/dd" format?

What's the code converting it on the C# side? For example, it could well be culture-specific to wherever the server is. — Jon Skeet
– Jon Skeet, Commented Jul 30, 2013 at 14:40
The code on the server side is just CheckDate(@model.Dated) It's just a DateTime C# object. — DK ALT
– DK ALT, Commented Jul 30, 2013 at 14:44

Scott Mermelstein · Accepted Answer · 2014-03-07 16:29:49Z

63

Given the output you're stuck with, I can't think of any better way to catch a DateTime of 0 on the javascript side.

Date.parse should work for your parsing needs, but it returns number of milliseconds, so you need to wrap a Date constructor around it:

var date = new Date(Date.parse(myCSharpString));

~~For the return date, you simply want~~

date.getFullYear() + "/" + (date.getMonth() + 1) + "/" + (date.getDate() + 1);

(date.getMonth and date.getDate are 0-indexed instead of 1-indexed.)

~~Fiddle: http://jsfiddle.net/GyC3t/~~

EDIT Thanks to JoeB's catch, let me do a correction. The date.getMonth() function is 0-indexed, but the date.getDate() function is 1-indexed. The fiddle was "working" with the +1 because date.getMonth works in local time, which is before UTC. I didn't properly check the docs, and just added 1, and it worked with the fiddle.

A more proper way to do this is:

For the return date, you simply want

date.getFullYear() + "/" + (date.getMonth() + 1) + "/" + (date.getUTCDate());

(date.getMonth is 0-indexed while date.getDate is 1-indexed but susceptible to time-zone differences.)

Fiddle: http://jsfiddle.net/GyC3t/25/

edited Mar 7, 2014 at 16:29

answered Jul 30, 2013 at 14:46

Scott Mermelstein

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5 Comments

JoeB Over a year ago

Javascript date months are 0 indexed, but day are 1 indexed.

Scott Mermelstein Over a year ago

@JoeB Wow. That was horrible of me. Thanks for catching that!

Anirudha Gupta Over a year ago

I want to get the month and date in 2 digit, any idea for do it in inside javascript ?

Scott Mermelstein Over a year ago

@Gupta Your comment is imprecise. I already give 2 digit answers. If you want to know how to zero pad a number like 4 to 04, you really just want to do a Google search for "zero pad javascript". Here's one of the first answers that pops up: stackoverflow.com/questions/10073699/…

RobG Over a year ago

new Date(Date.parse(myCSharpString)) will produce an identical result to new Date(myCSharpString), the use of Date.parse is entirely redundant.

Nick Gotch · Accepted Answer · 2013-07-30 14:55:20Z

2

I use the following to pass a Javascript Date into C#:

var now = new Date();
var date = (now.getTime() / 86400000) - (now.getTimezoneOffset() / 1440) + 25569;

So if you get the number of milliseconds from C#, it should be something like this:

var csharpmilliseconds;
var now = new Date();
var date = new Date((csharpmilliseconds + (now.getTimezoneOffset() / 1440) - 25569) * 86400000);

answered Jul 30, 2013 at 14:55

Nick Gotch

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Comments

vikingfabian · Accepted Answer · 2022-03-10 11:24:21Z

2

I made a variant, that I think is a bit more readable

/// <summary>
/// Start of Javascript Date
/// </summary>
static readonly DateTime UnixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);

/// <param name="ms">From js Date.getTime()</param>
/// <returns>Date in UTC, use ToLocalTime()</returns>
public static DateTime FromJavascriptMs(string ms)
{
    var millisec = double.Parse(ms);
    DateTime result = UnixEpoch.AddMilliseconds(millisec);
    return result;
}

public static double ToJavascriptMs(DateTime date)
{
    TimeSpan duration = date.Subtract(UnixEpoch);
    return duration.TotalMilliseconds;
}

answered Mar 10, 2022 at 11:24

vikingfabian

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