Follow the great instructions at https://github.com/janet-lang/janet
I highly recommend using the straight package manager
(straight-use-package
'(ijanet
:type git
:host github
:repo "serialdev/ijanet-mode"
))
Alternatively pull the repo and add to your init file
git clone https://github.com/SerialDev/ijanet-mode
Janet is required
C-c C-p [Start repl] (ijanet)
C-c C-b [Eval buffer] (ijanet-eval-buffer)
C-c C-l [Eval line] (ijanet-eval-line)
C-c C-r [eval region] (ijanet-eval-region)