Hi everyone,
I found an interesting multiplatform application called NightPDF … you can find it here
I looked in the AUR repository but it seems to be an old version 0.2.1.r1
with the clone git command how can i install this application ?
Thanx a lot everyone ! 
Normally with
yay -S nightpdf-git
Note that as it is a -git package, it should install the latest (=development) version available from github.
Version 0.2.1.r1 is simply the version it was initially when added to AUR. The PKGBUILD has function pkgver() that changes the version when you build it locally.
You can see it from the PKGBUILD:
https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=nightpdf-git
EDIT: looks like there’s something strange in the package, so I’d be cautious with it.
The PKGBUILD on the AUR page is different from what you get with yay -Ga nightpdf.
To me it seems like a warning…
Sorry, ignore the warning above. My fingers wrote a wrong package name… 
Finally I have succeeded to install NightPDF …
I installed yarn before and I type:
git clone https://github.com/Lunarequest/NightPDF.git
yarn
yarn dist
An appimage of NightPDF 1.07 was created in the dist folder
and an installation was done in “linux-unpacked” so I could launch nightPDF from that directory …
I also could launch the appimage and include it with “appimage-launcher” I had already installed !
Everything is on the page of the project
yarn
yarn dev
yarn
yarn dist
Thanks for your help !
and the gif from github that lets you see some possibilities of NightPDF
