Semantic Versioning

About

Semantic Versioning (SemVer) is a versioning system that help us keep track of what’s going on in projects.

SemVer is a 3-component system in the format:

• x stands for a major version
• y stands for a minor version
• z stands for a patch

Major.Minor.Patch, increment cases:

• Major version when you make incompatible API changes
• Minor version when you add functionality in a backwards-compatible manner
• Patch version when you make backwards-compatible bug fixes

Benefits

• keep a semantic historical track of a component
• know which version of a component is no longer backwards compatible
• avoid dependency hell when using a component in different places
• allow a component to be distributed correctly with package managers

Pre-release

With Semantic Versioning, pre-releases can be defined by appending a hyphen and an identifier to a version. For example:

• 1.0.0 -> 1.0.0-alpha.1
• 1.0.0 -> 1.0.0-alpha.2

How to use that

There are two ways for requiring a lib via semver number.

• Static: eg: "fancylib": "1.5.4". This mean that you'll get fancyLib version 1.5.4 and that will be fixed in the project. npm install / npm update will not change that version
• Dynamic. You can use this three symbols ^ ~ * when you specify the semver
  • ^ this can be used at the beginning of the semver. this means that you'll get the latest minor and patch updates for the specified major
  • ~ this can be used at the beginning of the semver. this means that you'll get the latest patch updates for the specified major.minor
  • *This is a wildcard, let's see how it works
    • *.0.0 you'll get the latest major, minor , patch
    • 3.*.0 you'll get the latest minor , patch for the major 3 the same as ^
    • 3.9.* you'll get the latest patch for major 3, minor 9, the same as ~

Is that tricky? You can check what your semver will download in your codebase using this handy tool!

Resources

• Official website semver.org