Lead Maintainer: Nicolas Morel
Imagine you run facebook and you want visitors to sign up on the website with real names and not something like
l337_p@nda in the first name field. How would you define the limitations of what can be inputted and validate it against the set rules?
const Joi = ;const schema = Joiobject;// Return result.const result = Joi;// result.error === null -> valid// You can also pass a callback which will be called synchronously with the validation result.Joi; // err === null -> valid
The above schema defines the following constraints:
Usage is a two steps process. First, a schema is constructed using the provided types and constraints:
const schema =a: Joi;
Note that joi schema objects are immutable which means every additional rule added (e.g.
.min(5)) will return a
new schema object.
Then the value is validated against the schema:
const error value = Joi;// orJoi;
If the input is valid, then the error will be
null, otherwise it will be an Error object.
const schema = Joi;
If the schema is a joi type, the
schema.validate(value, callback) can be called directly on the type. When passing a non-type schema object,
the module converts it internally to an object() type equivalent to:
const schema = Joiobject;
When validating a schema:
Values (or keys in case of objects) are optional by default.
Joi; // validates fine
To disallow this behavior, you can either set the schema as
required(), or set
"required" when passing
Strings are utf-8 encoded by default.
Rules are defined in an additive fashion and evaluated in order after whitelist and blacklist checks.
See the API Reference.
Joi doesn't directly support browsers, but you could use joi-browser for an ES5 build of Joi that works in browsers, or as a source of inspiration for your own builds.