Developing with NPM & GitHub branches

April 25, 2016

Much of my recent work at Mapbox has been around developing and testing node modules lay the groundwork of our vector tile pipeline. All of our node modules that we use across tools, such as tilelive, are published to NPM, which means we release semantically versioned updates.

When developing NPM hosted packages, it can become a pain to constantly push updates to NPM especially since this can have effects on others using your modules. We want to be able to test changes of node modules across our team and pipeline without relying on NPM’s publishing service.

A quick way around this is to use GitHub as a means of testing development versions, without publishing to NPM.

Say we have two repositories, lemon and fruit-basket. The fruit-basket module relies on lemon as a dependency in it’s package.json file:

{
  "name": "fruit-basket",
  "description": "A basket of fruits",
  "version" : "0.1.0",
  "repository": {
    "type": "git",
    "url": "git://github.com/mapsam/fruit-basket.git"
  },
  "dependencies": {
    "lemon": "1.0.0"
  }
}

If we were developing lemon@2.0.0 and wanted to make sure fruit-basket still worked, you could publish dev versions to NPM like lemon@2.0.0-dev if you wanted, but that’s an unecessary step.

Since lemon is a GitHub repository, we can actually point the dependency version at a GitHub branch! Assuming lemon@2.0.0 is being developed on the big-update branch, we can update our package.json to the following:

{
  "dependencies": {
    "lemon": "https://github.com/mapsam/lemon/tarball/big-update"
  }
}

Pretty neat! Now if you remove your node_modules directory in fruit-basket and re-install all of your dependencies, you’ll notice the version of lemon you are pointing at is 2.0.0. You can check what version of a dependency you are using by running npm ls lemon.

Bonus points

You can point your dependencies at more than GitHub branches! You can point to gitsha’s and releases as well. As of NPM 1.1.65 you don’t even need the github prefix.

{
  "dependencies": {
    "lemon": "git://github.com/mapsam/lemon.git#gitsha",
    "lemon": "git://github.com/mapsam/lemon.git#release",
    "lemon": "mapsam/lemon",
    "lemon": "mapsam/lemon#gitsha",
    "lemon": "mapsam/lemon#release"
  }
}

Save your publishing to NPM for real releases!

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