Validation types

array(config?, itemValidator, ...arrayValidators)

Casts value to an array, null or undefined if using the default array parser.

config is optional and may include the following properties:

• parser can be set to customize how to parse and transform the value being validated.
• default to be used as the fallback value in case the parser returns undefined.

itemValidator is the validator to be applied on each value within the array and may be any type validator:

• array
• boolean
• date
• number
• object
• string

arrayValidators are the remaining checks to be applied to the array as a whole and can be any of the following validation tests:

• max
• min
• required

boolean(config?, ...validators)

Casts value to a boolean, null or undefined if using the default boolean parser.

config is optional and may include the following properties:

• parser can be set to customize how to parse and transform the value being validated.
• default to be used as the fallback value in case the parser returns undefined.

validators may be any of the following validation tests:

• oneOf
• required

date(config?, ...validators)

Casts value to a date, null or undefined if using the default date parser.

config is optional and may include the following properties:

• parser can be set to customize how to parse and transform the value being validated.

  The default parser only accepts dates, numbers, and a subset of ISO 8601 formatted strings (excludes week formats). If you want to allow other or more complex formats you should use a third-party library such as date-fns or Day.js.

• default to be used as the fallback value in case the parser returns undefined.

validators may be any of the following validation tests:

• maxDate
• minDate
• oneOf
• required

number(config?, ...validators)

Casts value to a number, null or undefined if using the default number parser.

config is optional and may include the following properties:

• parser can be set to customize how to parse and transform the value being validated.
• default to be used as the fallback value in case the parser returns undefined.
• round sets which, if any, rounding method to use. Must be one of nearest, ceil, or floor. If not set, no rounding is applied.

validators may be any of the following validation tests:

• exact
• integer
• max
• min
• oneOf
• required

object(schema)

The only validation type that does not cast the entered value, meaning it does not use a parser. There's also no default fallback value option here. Instead, the schema is an object where its properties are validation types such as string, array, number, etc. Nested object validators are allowed, but not recommended due to their complexity and potential performance hit.

For invalid results, errors are in the errors property. It matches the provided object with the same keys and strings or string records as values that contain the error messages.

Unlike Yup, this API does not (yet at least) have a ref option.

To use this with a library such as Formik, you can use the resulting errors property. It is a key-value structure with the schema property keys and their validation errors if any. Besides that, the object validation results are the same as described above.

string(config?, ...validators)

Casts value to a string, null or undefined if using the default string parser.

config is optional and may include the following properties:

• parser can be set to customize how to parse and transform the value being validated.
• default to be used as the fallback value in case the parser returns undefined.
• trim will strip the whitespace from the start and end of the string when set to true. Defaults to false.

validators may be any of the following validation tests:

• email
• exact
• matches
• max
• min
• oneOf
• required
• url