Semantic versioning
Version numbers like 2.4.1 follow a pattern that tells you how risky an upgrade is.
In this page:
Syntax
"package_name": "MAJOR.MINOR.PATCH"
"package_name": "^MAJOR.MINOR.PATCH"
"package_name": "~MAJOR.MINOR.PATCH"Semantic versioning
Semver uses MAJOR.MINOR.PATCH. Patch fixes bugs, minor adds backward-compatible features, and major may break things. In package.json, a caret allows minor and patch updates, a tilde allows only patch updates, and an exact version pins it.
Note:
^1.2.3 allows anything from 1.2.3 up to (but not including) 2.0.0.
Example: Semantic versioning
function allowsCaret(range, version) {
const [rM, rm, rp] = range.replace("^", "").split(".").map(Number);
const [vM, vm, vp] = version.split(".").map(Number);
return vM === rM && (vm > rm || (vm === rm && vp >= rp));
}
console.log("^1.2.3 allows 1.9.0:", allowsCaret("^1.2.3", "1.9.0"));
console.log("^1.2.3 allows 2.0.0:", allowsCaret("^1.2.3", "2.0.0"));
console.log("^1.2.3 allows 1.2.2:", allowsCaret("^1.2.3", "1.2.2"));
// Output:
// ^1.2.3 allows 1.9.0: true
// ^1.2.3 allows 2.0.0: false
// ^1.2.3 allows 1.2.2: false⚠️ Run this in your own terminal or Node.js environment.
Related Topics
Common Mistakes
- Assuming any upgrade is safe
- Confusing caret and tilde
- Not committing the lock file
Chapter Summary
- MAJOR.MINOR.PATCH
- Caret allows minor and patch
- Tilde allows patch only
- Lock files pin exact versions
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