[+wf.subitemcount+] return the number of documents inside a folder, it’s not meant to be used the way you try.
Actually, if it’s unique from a CSS standpoint it would make more sense using an ID, and that’s why Wayfinder is not meant to output unique classes

(you could do that though, since TV placeholders are available since Wayfinder 2.0

)
Which means you should give a look at &rowIdPrefix which appends the document ID to the id.
Check the doc
&rowIdPrefix
default: FALSE
values: name of prefix
description: If this parameter is set, Wayfinder will replace the placeholder [+wf.id+] with a unique id consisting of the specified prefix plus the document id.
example: &rowIdPrefix=`topMenu` will output the following for doc # 29: id="topMenu29"
http://www.muddydogpaws.com/development/wayfinder/parameters.html
Hope it helps
.: COO - Commerce Guys - Community Driven Innovation :.
MODx est l'outil id
Thank for Your reply.
Sorry, I forget to say that menu items with nav1, nav2, .... go into (a part of) folder with Id=0.
This chage something in my question?
Thank again!
No it does not, [+wf.subitemcount+] return the number of documents inside a folder you can’t use it this way.
And CSS wise, using unique class doesn’t make much sense as I said... IDs is what you’re looking for if you need unique styling for your menu items... which brings me to the question : what are you trying to achieve, ultimately ?
.: COO - Commerce Guys - Community Driven Innovation :.
MODx est l'outil id
No problem, that’s what more proficient users are here for, help people who want to learn
.: COO - Commerce Guys - Community Driven Innovation :.
MODx est l'outil id