Regex cheatsheet
Javascript Regex/Regular Expression cheatsheet
| Expression | Description |
|---|---|
| . or [^\n\r] | any character excluding a newline or carriage return |
| [A-Za-z] | alphabet |
| [a-z] | lowercase alphabet |
| [A-Z] | uppercase alphabet |
| \d or [0-9] | digit |
| \D or [^0-9] | non-digit |
| _ | underscore |
| \w or [A-Za-z0-9_] | alphabet, digit or underscore |
| \W or [^A-Za-z0-9_] | inverse of \w |
| \S | inverse of \s |
| Expression | Description |
|---|---|
| space | |
| \t | tab |
| \n | newline |
| \r | carriage return |
| \s | space, tab, newline or carriage return |
Think of a character set as an OR operation on the single characters that are enclosed between the square brackets. Use ^ after the opening [ to "negate" the character set. Within a character set, . means a literal period.
| Expression | Description |
|---|---|
| [xyz] | either x, y or z |
| [^xyz] | neither x, y nor z |
| [1-3] | either 1, 2 or 3 |
| [^1-3] | neither 1, 2 nor 3 |
Outside a character set
| Expression | Description |
|---|---|
| \. | period |
| \^ | caret |
| \$ | dollar sign |
| | | pipe |
| \\ | back slash |
| \/ | forward slash |
| \( | opening bracket |
| \) | closing bracket |
| \[ | opening square bracket |
| \] | closing square bracket |
| \{ | opening curly bracket |
| \} | closing curly bracket |
A ^ must be escaped only if it occurs immediately after the opening [ of the character set. A - must be escaped only if it occurs between two alphabets or two digits.
| Expression | Description |
|---|---|
| \\ | back slash |
| \] | closing square bracket |
The quantifier goes after the expression to be quantified.
| Expression | Description |
|---|---|
| {2} | exactly 2 |
| {2,} | at least 2 |
| {2,7} | at least 2 but no more than 7 |
| * | 0 or more |
| + | 1 or more |
| ? | exactly 0 or 1 |
How word boundary matching works: At the beginning of the string if the first character is \w. Between two adjacent characters within the string, if the first character is \w and the second character is \W. At the end of the string if the last character is \w.
| Expression | Description |
|---|---|
| ^ | start of string |
| $ | end of string |
| \b | word boundary |
| Expression | Description |
|---|---|
| foo|bar | match either foo or bar |
| foo(?=bar) | match foo if it's before bar |
| foo(?!bar) | match foo if it's not before bar |
| (?<=bar)foo | match foo if it's after bar |
| (?<!bar)foo | match foo if it's not after bar |
Capturing groups are only relevant in the following methods: string.match(regexp), string.matchAll(regexp), string.replace(regexp, callback). \N is a backreference to the Nth capturing group. Capturing groups are numbered starting from 1.
| Expression | Description |
|---|---|
| (foo) | capturing group; match and capture foo |
| (?:foo) | non-capturing group; match foo but without capturing foo |
| (foo)bar\1 | \1 is a backreference to the 1st capturing group; match foobarfoo |
About this tool
Use it to
- Quick reference for regex syntax while coding
- Learn regex patterns and special characters
- Find the right quantifier or boundary for your pattern
- Understand character sets and escaping rules
- Basic Patterns
- Look up common patterns like \d for digits, \w for word characters, and \s for whitespace.
- Quantifiers
- Find the right quantifier like *, +, ?, or {n,m} for your matching needs.
Related tools
- Regex Tester
Test your regular expressions with sample text
- Git cheatsheet
Git is a decentralized version management software. With this cheatsheet, you will have quick access to the most common git commands
- shadcn/ui cheatsheet
Quick reference for shadcn/ui commands to add and manage components in your project
- SQL cheatsheet
Comprehensive SQL command reference for querying, managing, and formatting database results