tz_offset | Simple abstraction of a timezone offset | Date Time Utils library

Looks like you have few formatting issues with your resp field which you can fix with few REPLACEs as in below example

The problem is that you pass the function directly, hence when the freezegun overrides the datetime.now attribute, that has no impact on the references to the old function.

An alternative might be to make a custom function where you each time retrieve the attribute:

A good way to reduce for-loops into comprehensions, is to first visualize the process using a regular for loop:

You can reuse the even callback as many times as you want by binding it to multiple event listeners with el.onclick = setTimeFields or el.addEventListener('click', setTimeFields).

1. Element IDs must be unique: you cannot identify multiple elements with the same ID, you must use classes for that (see 2x button.classBtn instead of 2x button#btn).

2. this.children[2] will not make sense for both the button and the input - instead, we will go up to the parent, and then search it for the .timeField input and refer to that.

I cannot reproduce the example for datetime.datetime.now. pytz also shows the correct UTC offset change in 2017 for the timezone 'Africa/Khartoum'. However, you need to use the localize method (see e.g. here).

Just a simple list comprehension should be enough assuming you've managed to load the json into a dict.

These strings are known as POSIX timezones and are defined here. This definition says this about the UTC offset:

If preceded by a '-', the timezone shall be east of the Prime Meridian; otherwise, it shall be west (which may be indicated by an optional preceding '+' ).

Meanwhile std::put_time is defined in terms of the C/Posix strftime which says this about offset:

%z is replaced by the offset from UTC in the ISO 8601 format ‘‘−0430’’ (meaning 4 hours 30 minutes behind UTC, west of Greenwich), or by no characters if no time zone is determinable. [tm_isdst]

In summary, there's one convention for posix time zone strings (negative means east of the prime meridian), and another for just about everyone else, including other parts of posix (negative means west of the prime meridian).

So your code is actually getting the correct answer.

Fwiw, here is a C++17 free, open-source, header-only Posix time zone library which can to the job without changing the global environment variable TZ, and does it with simpler syntax: