Value of property before binding is executed in perspective

[pascal.fragnoud]

That's not how coalesce works. dateFormat will never return a null, so coalesce won't do anything.
try this instead:

if (isNull({this.custom.datetime}),
  "loading...",
  dateFormat({this.custom.datetime}, 'dd-MM hh:mm')
)

I suggest you read this:

Wiki - how to post code on this forum

This thread is intended as a short help file for all those struggling to post formatted code on the forum. Code block formatting Posting formatted code on the forum (and most others) is as simple as selecting the code and pressing the </> button. It works the same as applying Bold or Italic styles to your document. It preserves indentation and applies syntax highlighting. [How to post code] Note that all the </> button does is add three backticks ``` on the line before the code block and anot…

edit: that shift script looks funky to me. It seems dates are strings, but you're getting them from built-in features. There's something weird here.

edit again:
yep they're strings:

I'm not sure what it's supposed to represent, and there's no details in the docs