30-seconds-of-code/snippets/js/s/regexp-cheatsheet.md

title, type, language, tags, author, cover, excerpt, dateModified

title	type	language	tags	author	cover	excerpt	dateModified
Regular Expressions Cheat Sheet	cheatsheet	javascript	string regexp cheatsheet	chalarangelo	tools	Regular expressions are a very useful tool. Save this cheatsheet for when you need to look up their syntax and speed up your development.	2021-06-12T19:30:41+03:00

Anchors

• ^: start of the string or the start of a line in a multiline pattern
• $: end of the string or the end of a line in a multiline pattern
• \b: word boundary
• \B: not word boundary (opposite of \b)

Note: Anchors are non-quantifiable (i.e. cannot be followed by a quantifier).

Character sequences

• .: any character except line breaks
• \w: any word character
• \W: any non-word character (opposite of \w)
• \s: any whitespace character
• \S: any non-whitespace character (opposite of \s)
• \d: any digit character
• \D: any non-digit character (opposite of \d)
• [abc]: a single character in the given set (here a, b or c)
• [^abc]: a single character not in the given set (opposite of [abc])
• [a-z]: a single character in the given range (here between a and z inclusive)
• [^a-z]: a single character not in the given range (opposite of [a-z])
• [a-zA-Z]: a single character in either of the given ranges

Note: Use \ to escape special characters (e.g. \, /, [, ], (, ), {, } etc.).

Quantifiers

• a?: zero or one of a (equal to a{0,1})
• a*: zero or more of a (equal to a{0,})
• a+: one or more of a (equal to a{1,})
• a{3}: exactly 3 of a
• a{3,}: 3 or more of a
• a{3,5}: between 3 and 5 of a (inclusive)

Note: a is any valid quantifiable expression.

Groups

• (ab): match and capture everything enclosed (here exactly ab)
• (a|b): match and capture either one character (here a or b)
• (?:ab): match everything enclosed, without capturing

Flags

• g: Global
• m: Multiline
• i: Case insensitive
• u: Unicode

Note that this cheatsheet is meant only as a starting point and is by no means a complete guide to all the features and nuances of regular expressions. You can also read 6 JavaScript Regular Expression features you can use today for a deeper dive into some more advanced features.