# 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`)

## 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

## 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)

## 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.

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