You probably want Date.toLocaleFormat() - the optional parameters to toLocaleString() have only been added in Firefox 29, so until gjs updates its JS engine to the corresponding version (I wouldn't count on it for 3.14), your change will not have any effect at all. Also the language codes don't seem to match the ones used by gettext[0], so it might not even work when gjs starts to support the new parameters. [0] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl#Locale_identification_and_negotiation

Yes. I wanted to use Date.toLocaleFormat(), but then I saw this big red banner on that page [1]. So I decided to use Date.toLocaleString() [2] because in examples locale names was the same as in GNOME Shell (now I noticed, that gnome uses underscore en_US and javascript uses en-US). So I prepared some code in Firefox console and copied it to my extension.js. I tested it with different regions and it worked fine. When you mentioned using toLocaleFormat(), I decided to check it in lg console and it generates error. After it I decided to check toLocaleString() in lg console. The thing is it does exactly what I need (I checked it by changing locale settings to different regions), but it completely ignores locale and options arguments! So I think I just need to replace start_time.toLocaleString(locale, options) with start_time.toLocaleString(). [1] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toLocaleFormat [2] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toLocaleString

Well yes, the toLocaleString() options will be supported once gjs updates its JS engine (as mentioned before). If you read the toLocaleFormat() warning, it advises you to not use this non-standard feature on a page facing the public web - this obviously does not apply to gnome-shell/extensions. But sure, if you don't need more fine-grained control than date.toLocaleFormat('%c'), then date.toLocaleString() is perfectly fine.

Thanks! I will submit corrected version in a moment. By the way, could you please help me figure out how do settings works? For example, I have a key in my xml configuration file: <key name="show-seconds" type="b"> <default>false</default> <summary>Show seconds</summary> <description>Set to true to show seconds</description> </key> I would like to it to be shown in dconf editor as checkbox (helpful for debug), but it isn't shown at all! I looked through some others extensions which have the same checkbox I would like to have and I see no general difference in our xml files...

Yeah, dconf-editor only works for schemas that have been installed in the global schema dir. However after compiling your schema, something like gsettings --schemadir /path/to/extension/schema/dir your.extensions.schema.identifier show-seconds should work. But maybe it makes sense to follow the global clock-show-seconds in org.gnome.desktop.interface instead?