TIL: The Real Meaning of the Caret ^ Symbol in npm

Not my first rodeo

More than once, I have found myself deep diving into the possible causes of an issue with a dependency, only to find that the work had already been done by someone else. All I needed to do was update my dependency... So consider this a friendly reminder:

When debugging an issue with a dependency, checking whether its release notes mention your issue is always a good starting point.

Additionally, while you may interact more often with your package.json, the lockfile is the actual source of truth for what version of a package you're running.

Why updates are not automatic

You may already know that when working with semantic versioning in npm, as the user of a package, the ^ caret symbol signifies that you want to accept minor updates. But did you know that this doesn't mean that when you run npm install you'll necessarily get the latest version? Even within the bounds you specified?

In fact, you'll only get the latest version if either:

• You're installing the project for the first time
• You force an update with the npm update command

Otherwise, npm won't automatically re-resolve all versions and pull the latest matching ones.

The reason you may end up in this situation is because lockfiles are committed into source repositories, and the lockfile is the source of truth for which version you're running (you can run npm list <package-name> to check the version). So while you'll get the latest version when you first add a package with the ^ symbol, if a new version is published later on, you won't get it because the lockfile specifies the previous version, and nothing has prompted npm to re-resolve the versions.

My simple workflow

So here's a simple workflow to follow when dealing with issues related to a dependency:

1. Check which version you're running using the npm list command
2. Check the dependency's release notes to see whether your issue was fixed in a recent release
3. Update the dependency if your version does not include the fix

Hopefully, updating the dependency does not involve a major update with breaking changes. But even if it does, at least you'll know what's going on. Either way, the best way to avoid this kind of confusion is to stick with the best practice of regularly updating your dependencies.