regex pattern visualizer : regex101: build, test, and debug regex https://regex101.com/

regex

character

meaning

\d

digital characters

\D

not digital characters

\w

Matches any alphanumeric character from the basic Latin alphabet, including the underscore. Equivalent to [A-Za-z0-9_].

\W

Matches any character that is not a word character from the basic Latin alphabet. Equivalent to [^A-Za-z0-9_].

\s

Matches a single white space character, including space, tab, form feed, line feed, and other Unicode spaces. Equivalent to [\f\n\r\t\v\u0020\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff]. For example, /\s\w*/ matches " bar" in "foo bar".

\b

word boundary. "\baa\b.*" matches "aa bb", dose not match "aabb".

Lookaround

Name

What it Does

(?=foo)

Lookahead

Asserts that what immediately follows the current position in the string is foo

(?<=foo)

Lookbehind

Asserts that what immediately precedes the current position in the string is foo

(?!foo)

Negative Lookahead

Asserts that what immediately follows the current position in the string is not foo

(?<!foo)

Negative Lookbehind

Asserts that what immediately precedes the current position in the string is not foo

type

pattern

description

greedy

.*

matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)

lazy

.*?

matches the previous token between zero and unlimited times, as few times as possible, expanding as needed (lazy)

ref

Lookahead and Lookbehind Tutorial—Tips &Tricks

https://www.rexegg.com/regex-lookarounds.html

Regex Tutorial - Lookahead and Lookbehind Zero-Length Assertions

https://www.regular-expressions.info/lookaround.html

Regular expressions - JavaScript | MDN

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions

Character classes - JavaScript | MDN

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions/Character_Classes