Source: stackoverflow.com/questions/42004440/regex-to-match-4-letters-in-a-string

stackoverflow.com/questions/30648699/regular-expression-to-match-at-least-two-special-characters-in-any-order

From: stackoverflow.com/questions/12870489/regex-to-match-a-word-with-unique-non-repeating-characters

Regex validate PIN code (Solution www.codewars.com) https://www.codewars.com/kata/regex-validate-pin-code/javascript

This regex validates all dates between 01/01/1900 and 12/31/2099, including leap-year validation. It follows a mm/dd/yyyy format, and enforces two-digit month/year formats.

Selects the string after the $ sign