^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)$ Matches: ✓ 1.0.0 ✓ 2.5.13 ✗ 1.0 (missing patch)
^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)$
Full SemVer regex is much longer. This is the simplified MAJOR.MINOR.PATCH version.