normalize

Applies a named or custom normalizer to selected top-level fields.

normalize({
  createdAt: 'isoDate',
  balance: 'number',
  verified: 'boolean',
  total: 'currency:USD',
})(input);

Built-in normalizers

Spec	Accepted values	Output
isoDate	Date, date string, timestamp	ISO string or null
number	Finite number or numeric value accepted by Number()	number or null
boolean	booleans, 1/0, and case-insensitive true, false, yes, no, '1', '0'	boolean or null
currency:USD	Finite number or numeric value	locale-formatted string or null

Null, undefined, the empty string, and invalid built-in inputs normalize to null. Currency formatting uses the runtime's default locale, so exact punctuation and symbol placement can vary between environments. The currency code must be supported by Intl.NumberFormat.

Custom normalizers

A callback receives the current field value and its key:

const transform = normalize({
  username: (value, key) =>
    typeof value === 'string' ? value.trim().toLowerCase() : null,
});

Custom callbacks control their own fallback and error behavior. They also run for a configured key that is absent from the input, receiving undefined.

Normalization is shallow and does not mutate the input.