[pmwiki-users] Adding/subtracting days to ftime Page Text Variable

[kirpi at kirpi.it]

> The first page uses an earlier recipe from 2007
> [...]
> http://www.pmwiki.org/pmwiki/uploads/Cookbook/markupexpr.php

Thank you Petko for your explanation :-)
I tried and paste some of the markupexpr.php code into my config.php
Fearing that it could clash with the ftime in use today, I dared to
change any "ftime" occurrence with "meftime".
Yet, when in use in pages like Cookbook/CopyPasteCalendar it makes disasters :-)
Probably the game is much more complicated than I naively guessed.
(and yes, of course I do not understand what that code does, too complicated)

What if one need to subtract 1 or 2 days from a certain date?
Looking on Google, there seems to be many (supposedly) easy ways, for
instance this javascript
   yourDate.setDate(yourDate.getDate() - daysToSubtract);
which looks easy to understand, but at the end I cannot imagine a way
to actually use it on a wiki page.

Is there any workaround, please?
(if not, no problem: one cannot have everything in life)

Thanks again

Luigi