Speed up your shell prompt when using Node Version Manager

I absolutely hate using version managers like nvm and rvm.

These days I don’t run any project session management like tmuxinator and tend
to forget that I need to be switching Node.js versions depending on the project
I am on.

I know, I know… I really should get back to automating my project sessions a
bit more, that one’s on me. In a perfect world, every project I touch would be
Dockerized and everything would be amazing, but that’s sadly not the world we
live in.

Okay, so outside of my own “senior moments” with juggling versions, the bigger
problem I always had with these version managers (again, speaking directly about
both rvm and nvm) is that their initialization scripts that need to be
sourced tend to slow down your shell prompt.

I’m not talking about a few extra milliseconds, I’m talking about a noticeable
lag when starting up a new terminal.

Okay, so it’s like a ~1 second delay, pretty manageable for most people.

Not me though, I live in the terminal and use GNU Screen and am constantly
opening up new tabs, windows and virtual consoles like it’s my job.

Okay, so it’s kind of my job 😉

Even on brand new hardware, I’ve noticed this delay. Fortunately, I
got fed up with this a while back and set out to create a solution.

My thought was that most of the time I don’t need nvm available. The MVP of
this was to just source the nvm initialization script only when I needed it.

I even created a nice script that I could run so I didn’t have to keep looking
up what the command was.

That was the MVP and it worked somewhat well until I realized that I so rarely
was using nvm that it became a chore to remember what the hell I named that

The next iteration was to create a shell alias that would replace nvm with
some logic that would attempt to run the initialization script and THEN try to
run the real nvm which the initialization script made available:

function nvm {
  if [ -z ${NVM_DIR+x} ] then
    export NVM_DIR="$HOME/.nvm"
    [ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh"
    nvm "$@"

It works pretty great for the most part, the only exception being that if you
use GNU Screen like I do and run nvm prior to starting a screen session, nvm
won’t work inside any of your windows.

The bigger caveat there is that if you DON’T run nvm prior to starting your
screen session, you will need to run nvm in each window that you create.

Really just means I need to be mindful about trying to juggle Node.js versions
within a single screen session.

A bit more in the YMMV department, the aforementioned alias worked fantastic on
Debian stable which nvm was installed to ~/.nvm/.

If you’ve installed to another directory you may need to make some adjustments
to the path.

Also, Arch Linux’s AUR package for nvm comes with a helper script installed to
/usr/share/nvm/init-nvm.sh which can be sourced instead:

function nvm {
  source /usr/share/nvm/init-nvm.sh
  nvm "$@"
Josh Sherman - The Man, The Myth, The Avatar

About Josh

Husband. Father. Pug dad. Musician. Founder of Holiday API, Head of Engineering and Emoji Specialist at Mailshake, and author of the best damn Lorem Ipsum Library for PHP.

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