RegEx

Notes for RegEx respectively Regular Expressions.

Guide (german): https://t3n.de/news/regex-guide-t3n-552858/

Quick Start Cheat Sheet: https://www.rexegg.com/regex-quickstart.html

Advanced tutorial: https://www.rexegg.com/regex-disambiguation.html

Practical tutorial: https://regexone.com/

Regex with JavaScript: https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/#regular-expressions

Test Regex: https://regexr.com/

General Rules

Character Types

Type	Example
Literal	a b c 1 2 3
Meta characters	. [[ ] { } ? * + | ( ) ^ $

Meaning of meta characters

Meta Character	Example
Single Character	.
Character class digit	\d
Character class character	\w
Character class whitespace	\s
Inversion of character classes (Not)	\D, \W, \S
Character class range	[a-c]
Inversion of character class range	[^abc]
Grouping with alternatives	(Mon|Tues)day
Word and text boundaries	b ^ $

Quantifiers

Quantifier	Example
Zero or one character	?
Zero or more characters (Kleene Star)	*
One or more characters (Kleene Plus)	+
Three characters	{3}
Four to 20 characters	{4,20}