625447 - Javascript date's toString() produces different output on different platforms.

Status: RESOLVED INVALID

(Core :: JavaScript Engine, defect)

Description

[Mark K]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13

Use firefox 3.6.13 on windows and on linux and visit a page that has:

<script language="Javascript">
    Xmas95 = new Date("2009 06 12,12:52:39");
    alert(Xmas95.toString());
</script>


On Windows the timezone will be represented as full English words: "Eastern Daylight Time".  On Linux, the timezone will be represented as just the 3 letter code "EDT".


Reproducible: Always

Steps to Reproduce:
1. visit any page that calls a date object's toString() method on two different OS platforms.


Expected Results:  
The exact same date format should be produced by the same browser version.

The date format should not vary depending on the underlying OS as this makes it more difficult for web servers to accommodate different formats and test for different operating systems for a single browser.

Comment 1

[David Dahl :ddahl]

I am sure Javascript gets the TZ info from the OS. For JS to store and handle TZ codes it seems a bit much. You can avoid these problems by using a little bit more of the Date API: https://developer.mozilla.org/en/JavaScript/Reference/global_objects/date

Comment 2

[Boris Zbarsky [:bzbarsky]]

The spec says:

  15.9.5.2	Date.prototype.toString ( )
    This function returns a String value. The contents of the String are
    implementation-dependent, but are intended to represent the Date in the
    current time zone in a convenient, human-readable form.

Note the last bit.  If you're examining the results of toString() in code, you're probably not doing what you want to do.

In our case, we just call the C library function strftime with the %Z format for the timezone part of toString on dates.  What that does will depend on your C library implementation, and probably on your locale too.  Again, the idea is to be human-readable.

So this looks invalid to me.

Comment 3

[Brendan Eich [:brendan]]

Use toISOString (new in ES5) or else crack the date apart however you like with getFullYear(), getMonth() (note that it is 0-based), etc.

js> Xmas95 = new Date("2009 06 12,12:52:39");
(new Date(1244836359000))
js> print(Xmas95.toISOString());  
2009-06-12T19:52:39.000Z

/be