useLocalTimezone causes bad behavior

[rehevkor5]

If useLocalTimezone is set to true and the field value contains a time zone that differs from the local time zone, opening the picker will immediately change the time zone in the field to the local time zone, but does not make a corresponding change to the date/time. Thus, clicking in the field changes the time.

Instead, one of two things should happen:

1. If there is a pre-existing time zone in the field, opening the picker uses that time zone, and does not modify the value of the field, OR
2. The field is modified to match the local time zone, but correct changes are applied to the date & time values so that the actual UTC value remains the same.

Option 1 is obviously easier to accomplish.

[rehevkor5]

By the way I'd be happy to try to fix it if you can point me in the right direction.

[trentrichardson]

Hard to say exactly where it is without tracing it through, but this may be a start:

https://github.com/trentrichardson/jQuery-Timepicker-Addon/blob/dev/jquery-ui-timepicker-addon.js#L1174

(Also note that is the dev branch)

[magnetik]

Confirming it.

Go an input with a value (IE: 01/16/2013 18:00 +0000). When clicking on it (datePicker has option useLocalTimezone), the input is changed for +0100 (in my case)

[magnetik]

On line 1764 (dev branch) selectLocalTimeZone is called (from $.datepicker._updateDatepicker) with the arguments

• tp_inst (has tp_inst.timezone: "+0000")
• date: Wed Jan 16 2013 18:00:00 GMT+0100 (Romance Standard Time)

then tzoffset is read from date (line 1768) so it has value "+0100"
then if (tp_inst._defaults.timezoneIso8601) { is false so no effect
then you call tp_inst.timezone_select.val("+0100")so the value is changed even if it's not correct at all.

If I come up with some elegant solution I'll do a pull request.

[magnetik]

Moreover, you already does the selectLocalTimeZone in $.extend._injectTimePicker (line 456 in dev)

if (local_timezone == this.timezone) {
    selectLocalTimeZone(tp_inst);
} else {
    this.timezone_select.val(this.timezone);
}

Which does not modify anything is the local timezone is different of the parsed time zone.

I've made a pull request.