fnm doesn't give you any shorthands to install nightly builds, but you can
do that by manually passing a "dist mirror" with the --node-dist-mirror
flag.
Here's an example of installing Node 23.
To get a list of available versions run this:
fnm --node-dist-mirror https://nodejs.org/download/nightly/ ls-remote
To use and install nightly version run this:
fnm --node-dist-mirror https://nodejs.org/download/nightly/ use 23
# or
fnm --node-dist-mirror https://nodejs.org/download/nightly/ use v23.0.0-nightly202407253de7a4c374
Once you installed it you would be able to see that version in you list:
fnm ls
And use it without providing --node-dist-mirror
flag:
fnm use 23