Creates a nullish schema.

const Schema = nullish<TWrapped, TDefault>(wrapped, default_);



  • wrapped TWrapped
  • default_ TDefault


With nullish the validation of your schema will pass undefined and null inputs, and if you specify a default_ input value, the schema will use it if the input is undefined or null. For this reason, the output type may differ from the input type of the schema.

Note that nullish accepts undefined and null as an input. If you want to accept only null inputs, use nullable, and if you want to accept only undefined inputs, use optional instead. Also, if you want to set a default output value for any invalid input, you should use fallback instead.



The following examples show how nullish can be used.

Nullish string schema

Schema that accepts string, undefined and null.

const NullishStringSchema = nullish(string(), "I'm the default!");

Nullish date schema

Schema that accepts Date, undefined and null.

By using a function as the default_ parameter, the schema will return a new Date instance each time the input is undefined or null.

const NullishDateSchema = nullish(date(), () => new Date());

Nullish entry schema

Object schema with a nullish entry.

const NullishEntrySchema = object({
  key: nullish(string()),

Unwrap nullish schema

Use unwrap to undo the effect of nullish.

const NullishNumberSchema = nullish(number());
const NumberSchema = unwrap(NullishNumberSchema);

The following APIs can be combined with nullish.




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