Regular expressions

A regular expression (shortened as regex or regexp; sometimes referred to as rational expression ) is a sequence of characters that specifies a match pattern in text. Usually such patterns are used by string-searching algorithms for “find” or “find and replace” operations on strings, or for input validation.

Resources

• RegExr

  • Learn, Build & Test RegEx

• regex101

  • build, test, and debug regex

• Mozilla Developer Network
• Microsoft
• txt2re

Often used snippets

Lines with nothing but whitespace

^(\s)*$\n