Npm Overrides

Hey! Recently I’ve been putting together a small program to track the temperature inside of a hand-me-down fridge. I’d planned to use my Nordic Thingy52 as it has all the sensors I need plus its own power source, but unfortunately I found that its NodeJS reference implementation was built with an abandoned Bluetooth Low Energy library which has stopped working with OSX after High Sierra.

Error: Cannot find module 'xpc-connection'
Require stack:
- /Users/scottomalley/Projects/Nordic-Thingy52-Nodejs/node_modules/noble-device/node_modules/noble/lib/mac/highsierra.js
- /Users/scottomalley/Projects/Nordic-Thingy52-Nodejs/node_modules/noble-device/node_modules/noble/lib/mac/bindings.js
- /Users/scottomalley/Projects/Nordic-Thingy52-Nodejs/node_modules/noble-device/node_modules/noble/lib/resolve-bindings.js

Thankfully a few fine folks came together to create @abandonware and have forked and updated noble, and a quick hack of replacing the existing noble reference with the @abandonware one on the surface seems to resolve my problem, but I don’t think this is a particularly elegant solution.

Replacing a dependency of a dependency

Digging into the Thingys Node library we can see that it’s not actually relying directly on Noble. Instead it uses a small wrapper made by the same author called noble-device. Meaning I can’t just replace the noble dependency the way I’d done in my quick fix previously.

$ npm list --depth 1
thingy52@1.0.4
└─┬ noble-device@1.4.1
 └── noble@1.9.1

npm overrides

npm version 8.3 was released in December 2021 and while it’s a minor release it did include a very useful feature “overrides”. npm overrides as the name describes lets you replace a dependency in your tree. Previously the only way to do nested dependency control was to fork and fix it yourself, so this is a welcome change that brings npm inline with similar features in yarn and pnpm Looking at our dependency tree above, if we were to go the forking route we’d have to fork noble-device to update its version of noble and either fork thingy52 or get a PR opened to the base repo to use our forked version. But with overrides we can add the following to our package.json

"overrides": {
   "noble-device": {
       "noble": "npm:@abandonware/noble@1.9.2-15"
   }
}

which will instruct npm to install our override in place of the original dependency.

$ npm list --depth 1
thingy52@1.0.4
└─┬ noble-device@1.4.1
 └── noble@npm:@abandonware/noble@1.9.2-15

There are a number of ways you can customise which dependency is replaced and in what situation. You can also be more targeted by specifying only to replace in certain situations. Below we only replace foo if bar is version 2.0.0

"overrides": {
   "bar@2.0.0": {
     "foo": "1.0.0"
   }
 }

You can also use it to standardise across your project. The below override will make foo always be v1.0.0 regardless of what any dependency requests.

{
 "overrides": {
   "foo": "1.0.0"
 }
}

Additionally it’s important to note that the overrides only take effect in the top level project. This means if I was to PR the change to the Thingy library, it would only work if I was running the Thingy library itself. To have it take effect in my own project I need to specify it there.

With the override in place if we run our original example from the Thingy reference library it will successfully execute and start looking for the Thingy

node ./examples/environment.js
Reading Thingy environment sensors!

With that solved I’m able to continue with my temp tracking project for the fridge!

Hopefully this helps anyone who is looking to fix broken dependencies!

Replacing a dependency of a dependency#

npm overrides#

Replacing a dependency of a dependency

npm overrides