deciding is hard…

Choosing the “right” NPM Package

Morgan Benton
Sep 10 · 5 min read

Recently I was developing a new custom package and I had a need for a list of US states to populate the state field in an address form. Perhaps the most straightforward thing to do would be to head on over to Wikipedia and manually compile our list. However, if you think about it, this is such a common task, it’s almost guaranteed that some programmer out there has already solved this problem for us. Sure enough, a brief Google search yields several packages that look promising:

But how do you pick? There’s no kind of quality control on NPM. Literally anyone at any time can publish a package, and it doesn’t even have to have any running code in it! So, as a developer, it is up to you, on your own, to determine whether or not any of these packages will meet your needs. Here are the features of a package that I typically examine when making this kind of decision:

  • When was it published and how often has it been updated?
    The version number of the package and when it was last published are listed at the top of the package page on NPM. In general, anything that hasn’t been updated in over a year (or never) should be treated with suspicion. (With USA state data, however, the actual list of states hasn’t really changed in a while, so this might not be a problem in this particular case.)
  • How many other people are using it?
    Every NPM page shows a sparkline chart of the package’s download history. If a package is being consistently downloaded hundreds or thousands of times a week, it’s a pretty good bet that many other developers have found it robust and reliable enough to include in their packages. I’ll only consider a package with few downloads if it is very new, i.e. published for the very first time within the last couple of months.
  • How good is the documentation?
    Good packages have great documentation. The NPM page (which mirrors the README from the GitHub repo where the packages usually live) typically explains what the package is, how to install it, how to use it, and gives clear examples of common usage scenarios. Sometimes I’ll use a package that forces me to dig into the source code to learn how to use it, but not often.
  • How responsive are the maintainers to support requests?
    Finally, I’ll head over to the GitHub repo where the package is maintained and look at the “Issues” and “Pull requests.” What is the ratio of open to closed issues? How quickly do the maintainers respond to questions or bug reports? How quickly do they respond to pull requests from the community? Are they courteous to the people who post questions and PRs? You might also search for the package on Stack Overflow and see if questions are being answered there.

None of these criteria are absolute. You have to take them all into account before reaching a decision. For a simple package, like providing the list of US states, you don’t really expect there will be many issues. Likewise, the code is likely so simple that it’s not an issue if it hasn’t been upgraded in a while. In the case of us-state-codes their sparkline shows a period of time when they were getting about 20,000+ downloads per week (DPW)(this is A LOT)! This started suddenly in October of 2018 and ended just as suddenly in February of 2019. I couldn’t really figure out why. Since then they’ve been getting a consistent 3,000 DPW. This is still quite respectable and more than the roughly 2,000 DPW that usa-states has been getting. On the other hand, state-list is getting only about 3 downloads per week and never got above the mid-20s. That’s not good.

All of that said, usa-states has clearer documentation, and provides something much closer to what we actually need than does us-state-codes. Plus, usa-states provides TypeScript type declarations, which is great since we’re developing with TypeScript. If a package is getting a couple thousand downloads per week, you can have a certain confidence that even if the original developer/maintainer decides to abandon the package, it will be important enough to someone to take over maintenance and keep it alive. And that’s probably the most important thing to look for. In this case, anyway, it’s enough for me to overlook the fact that usa-states’ current version number is a very low v0.0.5 and it hasn’t been updated in nearly 2 years.

One last thing to consider is package weight. How big (in kb) is the package you’re planning to use? Are you planning to use enough of it’s functionality to justify making people who use your package download their package as well? In the case of usa-states, the estimated download size is only 1.8kb (minified, gzipped), and that’s pretty darn small. If a package gets up into the tens or hundreds of kb, you might want to consider re-implementing just the parts you need manually in your own package.

And Even Then…

It’s easy to make a mistake. I ended up using usa-states for my project and quickly found that those TypeScript type declarations (you know, one of the main reasons I picked this one) were wrong. There was even a pull request on the repo with updated types to fix the bad ones. The PR had even been merged. Unfortunately, the package owner hadn’t taken the final step of updating the package in the NPM repository. 😞 That said, patching the TypeScript definitions for this package was still easier and faster than re-implementing my own solution from scratch (but probably not much). And I’m still grateful to the developers who were generous enough with their time, energy, and expertise to share their solution with me.


As globally available repositories of open-source packages have grown larger, it would be crazy for us developers not to piggy-back on one another. As Isaac Newton famously said, “We stand but on the shoulders of giants.” Just be careful about which “giant” you pick!

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