Regular Expressions Cheat Sheet

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.