typia/src/internal/_isFormatIpv4.ts

Superfast runtime validators with only one line

export const _isFormatIpv4 = (str: string): boolean => PATTERN.test(str);

const PATTERN =
  /^(?:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)\.){3}(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)$/;