How to Ensure Library B Uses the Same Version of Library C as My App

[maliknajjar]

Hello,

I have a scenario where my application imports Library B, and both my app and Library B rely on Library C. I want to ensure that Library B uses the same version of Library C as my application.

How can I enforce this in Deno?

[marvinhagemeister]

This is solved by both libraries specifying a version range instead of an exact version. Example:

• lib-b depends on lib-c@^1.0.0 (note the ^ character)
• your app depends on lib-c@^1.1.0 (again, note the ^ character)

This will install lib-c only once and both your app and lib-b will share the exact same version. This will always be the case for as long as the version ranges match. A scenario where they would not match would be where your app depends on lib-c@^3.0.0 but lib-b depends on lib-c@^1.0.0. No version of lib-c can satisfy both version constraints, so you'll end up with two copies.

To see all available version constraint characters, check out this page in the docs. Note that version specifiers only work with jsr: and npm: imports and not with http: or https:.

In the Node ecosystem you'll come across the term peerDependencies quite a bit which is kinda the same as version constraint, with the additional feature that package managers print a big warning or error when the version ranges don't match. Deno supports this, when you're defining your dependencies in package.json as well. That said for Deno first projects that is usually not needed and specifying correct version ranges is enough.