Examples.md

Regex Examples

IPv4 address validation

// Match integers from 0-255
const octet = choiceOf(
  [digit],
  [charRange('1', '9'), digit],
  ['1', repeat({ count: 2 }, digit)],
  ['2', charRange('0', '4'), digit],
  ['25', charRange('0', '5')]
);

// Match
const regex = buildRegExp([
  startOfString, //
  repeat([octet, '.'], { count: 3 }),
  octet,
  endOfString,
]);

This code generates the following regex pattern:

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