Regex to validate semantic versions

This is the official pattern from the semver.org spec 1, which rejects leading zeros:

const SEMVER =
  /^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$/;

It captures major, minor, patch, pre-release and build in groups 1 to 5. Strings like 1.2 or 01.2.3 fail, which is what you want.