Custom withDefault function

[sillvva]

Wrote a custom withDefault function, because the existing one didn't work for my needs.

This one converts falsy values or (in the case of numbers) NaN values to the default value.

import type { BaseSchema, BaseSchemaAsync, Input, ValidateInfo } from "valibot";

export function withDefault<TSchema extends BaseSchema | BaseSchemaAsync>(schema: TSchema, value: Input<TSchema>) {
	return {
		...schema,
		parse(input: Input<TSchema>, info?: ValidateInfo) {
			return schema.parse(!input || (typeof value == "number" && isNaN(input)) ? value : input, info);
		}
	};
}

Leaving this here, in case anyone else finds it useful.

[fabian-hiller]

Yes, the fact that you can easily write your own methods and schemas is the cool thing about Valibot. 🧩 withDefault is currently only used explicitly for undefined values. Since we are revising withDefault at the moment, I will take a look at that again.

Since the default value is only applied to undefined, withDefault works with any schema. However, I am aware that there are use cases where you might want to use a default value also in the case of null or a falsy value, for example.