Check Version Compatibility — Does Your Dependency Work?

Checking Version Compatibility

Version compatibility is the practical question behind semver: can I safely upgrade from version A to version B without breaking my code?

The Compatibility Contract

SemVer provides a contract between publishers and consumers:

Change Type	Compatibility	Safe to Upgrade?
Patch (1.2.3 → 1.2.4)	Backwards-compatible bug fix	✅ Always
Minor (1.2.3 → 1.3.0)	Backwards-compatible feature	✅ Usually
Major (1.2.3 → 2.0.0)	Breaking change	⚠️ Review required

How to Check Compatibility

Step 1: Identify the change type

Compare the two versions to see what changed:

• 1.2.3 → 1.2.4 — Patch change
• 1.2.3 → 1.3.0 — Minor change
• 1.2.3 → 2.0.0 — Major change

Step 2: Check your range

Does your package.json range allow the new version?

• ^1.2.3 allows up to <2.0.0 — accepts 1.2.4 and 1.3.0, rejects 2.0.0
• ~1.2.3 allows up to <1.3.0 — accepts 1.2.4, rejects 1.3.0

Step 3: Verify with tests

Even compatible versions can introduce subtle changes. Always run your test suite after updating.

Compatibility Matrix

For a project depending on ^1.2.3:

Candidate	In Range?	SemVer Compatible?	Action
1.2.4	✅	✅ Bug fix	Update freely
1.3.0	✅	✅ New feature	Update, review new features
1.9.0	✅	✅ New features	Update, check deprecations
2.0.0	❌	❌ Breaking	Read migration guide
1.2.3-beta.1	❌	N/A	Pre-release, explicit opt-in

Cross-Ecosystem Compatibility

Different ecosystems interpret compatibility slightly differently:

Ecosystem	Tool	Default Range
npm	npm/yarn/pnpm	Caret (^)
Rust	Cargo	Caret (^)
Python	pip	Usually >= with upper bound
Go	go mod	Minimum version selection
Ruby	Bundler	Pessimistic (~>) ≈ tilde

When SemVer Breaks Down

SemVer is a social contract, not a guarantee. Some packages:

• Make breaking changes in minor versions
• Consider CSS changes as "non-breaking" (debatable)
• Have different compatibility rules for different APIs within the same package