Javascript new Date(str) - different parsing rules - javascript

I tried this in the Chrome JS console, with my locale time zone set as PST:
(new Date("07-15-2005"))
=> Fri Jul 15 2005 00:00:00 GMT-0700 (PDT)
(new Date("07-15-2005")).getTime();
=> 1121410800000
but....
(new Date("2005-07-15"))
=> Thu Jul 14 2005 17:00:00 GMT-0700 (PDT)
(new Date("2005-07-15")).getTime();
=> 1121385600000
I was expecting string parsing to occur in both. But I can't make out why when format YYYY-MM-DD is used, it assumes a timezone offset. It's as if I'm expressing "2005-07-15" in my local TZ, but "07-15-2005" is expressed in UTC.
Is the correct explanation?

The implementation seems to be vendor specific, however looking at the documentation of date parse we see that as of 1.8.5 javascript supports both RFC2822 dates and ISO 8601 dates.
As per the Date.UTC documentation ISO 8601 dates are assumed to be in UTC time if not otherwise specified and thus the timezone difference is automatically added.
RFC2822 dates seem to be assumed as local times and as such are not modified.

I cannot seem to replicate your results, but the results seem to differ from browser to browser.
See: http://jsfiddle.net/f7DMV/
In Firefox and Opera, I get only the middle line parsing correctly, the others are Invalid Dates.
In Chrome, both the first and the second line parse correctly (and don't differ), but the last one is still Invalid.

It will vary from browser to browser. The ECMA262 spec says any string which is not in YYYY-MM-DD format and is passed to the Date function, it may fall back to implementation-specific heuristics or implementation-specific date formats.

Related

String to date converter issue in js

My local machine in EST timezone.
I'm trying to convert date string to date object in js but getting an day before from date string in date object.
new Date('2020-04-03') for this i'm getting Thu Apr 02 2020 20:00:00 GMT-0400 (Eastern Daylight Time) this output.
new Date('2020/04/03') for this i'm getting Fri Apr 03 2020 00:00:00 GMT-0400 (Eastern Daylight Time) this output.
console.log(new Date('2020-04-03'))
console.log(new Date('2020/04/03'))
I don't know what is the difference between these can anyone explain that?
How i fix this issue?
The reason why the two date parsings give you different results is because it's triggering two different date handling modes.
In one case, 2020-04-03, it's treating the date as an simplified version of ISO 8601 format, for which JavaScript creates a date in the UTC time zone if no time zone is specified.
The second date, 2020/04/03, is not in an officially supported format, so JavaScript falls back to an implementation-specific parsing of the date, so it may not even be consistent across browsers. In that case, it's choosing to use your local time zone.
The MDN article on Date.parse() offers a detailed explanation of how date parsing works in the JavaScript standard and how non-standard behaviors exist among browsers in some cases.
In short, it's a good idea to stick with ISO 8601 dates whenever possible, not only because JavaScript handles them in a consistent way, but they're also easily sorted, and they're widely supported across many programming systems.
Try new Date('2020-04-03 00:00:00')
By default, the date string is parsed in UTC timezone. When you output a date, by default it converts it to your local timezone set by your browser.
To solve, you can enter your date as the UTC equivalent, or simply do as the others have stated here and include the timezone in your date string
let date = new Date('2020-04-03 EST');

Safari and Chrome showing different results of new Date() [duplicate]

I want to convert date string to Date by javascript, use this code:
var date = new Date('2013-02-27T17:00:00');
alert(date);
'2013-02-27T17:00:00' is UTC time in JSON object from server.
But the result of above code is different between Firefox and Chrome:
Firefox returns:
Wed Feb 27 2013 17:00:00 GMT+0700 (SE Asia Standard Time)
Chrome returns:
Thu Feb 28 2013 00:00:00 GMT+0700 (SE Asia Standard Time)
It's different 1 day, the correct result I would expect is the result from Chrome.
Demo code: http://jsfiddle.net/xHtqa/2/
How can I fix this problem to get the same result from both?
The correct format for UTC would be 2013-02-27T17:00:00Z (Z is for Zulu Time). Append Z if not present to get correct UTC datetime string.
Yeah, unfortunately the date-parsing algorithms are implementation-dependent. From the specification of Date.parse (which is used by new Date):
The String may be interpreted as a local time, a UTC time, or a time in some other time zone, depending on the contents of the String. The function first attempts to parse the format of the String according to the rules called out in Date Time String Format (15.9.1.15). If the String does not conform to that format the function may fall back to any implementation-specific heuristics or implementation-specific date formats.
To make the Date constructor not (maybe) use the local timezone, use a datetime string with timezone information, e.g. "2013-02-27T17:00:00Z". However, it is hard to find a format that is reliable parsed by every browser - the ISO format is not recognised by IE<8 (see JavaScript: Which browsers support parsing of ISO-8601 Date String with Date.parse). Better, use a unix timestamp, i.e. milliseconds since unix epoch, or use a regular expression to break the string down in its parts and then feed those into Date.UTC.
I found one thing here. It seems the native Firefox Inspector Console might have a bug:
If I run "new Date()" in the native Inspector, it shows a date with wrong timezone, GMT locale, but running the same command in the Firebug Extension Console, the date shown uses my correct timezone (GMT-3:00).
Noticed that FireFox wasn't returning the same result as Chrome. Looks like the format you use in kendo.toString for date makes a difference.
The last console result is what I needed:
Try using moment.js. It goes very well and in similar fashion with all the browsers. comes with many formatting options. use moment('date').format("") instead of New Date('date')

Convert given UTC string and Timezone offset from JavaSscript to UTC format in SQL Server

I have been assigned a task where I have UTC string and timezone offset created in javascript code and they needs to be saved in sql server datetime column with UTC format.
UTC string is created as (new Date()).toUTCString();
Example: Thu, 03 Mar 2016 06:19:11 GMT and
Timezone is created as new Date().getTimezoneOffset();
Example: -330
Having no experience working with time zones, I am confused.
I think you're looking for Date.prototype.toISOString, which returns an ISO 8601 string in timezone UTC, e.g.
document.write( new Date().toISOString() );
The toUTCString method is implementation dependent, so not consistent across hosts. Also, the ECMAScript timezone offset has the opposite sense to ISO 8601 and those in common use, e.g. for a host set to UTC+5:00, getTimezoneOffset returns -300 (minutes).
If you need a pollyfill for toISOString to accommodate old hosts (e.g. IE 8), see MDN.

Date.parse() not working properly in Mozilla Firefox JavaScript

I have the string dateTime value "01-01-2013 12:00:00 AM" and parsed to DateTime using Date.parse("01-01-2013 12:00:00 AM"). This is working fine in Google Chrome and IE browser. But not working in Firefox. Anyone help how to parse this specific string to dateTime value in Mozilla Firefox.
Thanks,
Bharathi.
TL;DR You're using an invalid date format for this context, which Chrome and IE just happen to handle.
Full answer:
The specification only requires a JavaScript implementation to recognize certain formats in Date.parse. Specifically,
It accepts the RFC2822 / IETF date syntax (RFC2822 Section 3.3), e.g.
"Mon, 25 Dec 1995 13:30:00 GMT". It understands the continental US
time zone abbreviations, but for general use, use a time zone offset,
for example, "Mon, 25 Dec 1995 13:30:00 +0430" (4 hours, 30 minutes
east of the Greenwich meridian). If a time zone is not specified and
the string is in an ISO format recognized by ES5, UTC is assumed. GMT
and UTC are considered equivalent. The local time zone is used to
interpret arguments in RFC2822 Section 3.3 format (or any format not
recognized as ISO 8601 in ES5) that do not contain time zone
information.
ECMAScript 5 ISO-8601 format support
The date time string may be in ISO 8601 format. For example,
"2011-10-10" (just date) or "2011-10-10T14:48:00" (date and time) can
be passed and parsed.
Your example, 01-01-2013 12:00:00 AM, is not one of those formats. Some browsers may parse it anyway, depending on the JavaScript engine they are using, but it's non-standard. Chrome and IE happen to recognize it, but Firefox returns NaN, which is compliant with the spec:
The ECMAScript specification states: If the String does not conform to
the standard format the function may fall back to any
implementation–specific heuristics or implementation–specific parsing
algorithm. Unrecognizable strings or dates containing illegal element
values in ISO formatted strings shall cause Date.parse() to return
NaN.
See this documentation for more details.

what is wrong with this date format

This works in Chrome but not in Firefox.
new Date("2013-06-03 17:09:06-0400")
Works fine in Chrome
Gives 'NaN' in Firefox.
I would appreciate any help.
Take a look at Mozilla Developer Network's Date and Date.parse documentation.
Specifically, it states:
Alternatively, the date/time string may be in ISO 8601 format. Starting with JavaScript 1.8.5 (Firefox 4), a subset of ISO 8601 is supported. For example, "2011-10-10" (just date) or "2011-10-10T14:48:00" (date and time) can be passed and parsed.
If you throw a 'T' in between the date and the time you get:
new Date("2013-06-03T17:09:06-0400")
=> Mon Jun 03 2013 14:09:06 GMT-0700 (PDT)
In both Chrome and Mozilla, although you have to account for the the current timezone (thus PDT) of the user's system.
In my experience, the only reliable way to construct a date object from a string in JavaScript is to parse the string yourself, and then use the version of the constructor that takes a separate numeric parameter for each field.
The string-based constructor is far too prone to issues with locale-related parsing errors.

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