Create own plugins

Every implementation lets you register your own rules. A rule is a function that receives the rule arguments and returns a validator; the validator receives a value and returns an error code, or nothing if the value is valid. See How it works.

If a rule can be built from existing rules, you do not need code at all: use rules aliasing. Aliases are plain data and work in every implementation.

Rules that are useful across projects can be published as a package. See Extensions for examples, such as livr-extra-rules for JavaScript.