Regular expressions define search patterns for string matching, validation, text manipulation.

How to match exact words?

Use word boundaries: \bword\b matches 'cat' but not 'category'.

What does the cheat sheet include?

Common patterns: . (any), \d (digit), \w (word), \s (whitespace), ^ $ * + ? and character classes.

Regex Tester JavaScript Pattern Matcher with Explanation Offline

Cheat Sheet

. Any character

\d Digit (0-9)

\D Non-digit

\w Word char (a-z, A-Z, 0-9, _)

\W Non-word char

\s Whitespace

\S Non-whitespace

^ Start of string/line

$ End of string/line

* 0 or more

+ 1 or more

? 0 or 1 (optional)

{n} Exactly n times

{n,} n or more

{n,m} n to m times

[abc] Character set

[^abc] Negated set

(...) Capture group

(?:...) Non-capturing group

$1, $2 Back references

/ /

Test String

Match Information

Replacement String

Global (g) Case Insensitive (i) Multiline (m) Dot All (s) Unicode (u)

Result

What is Regex?

Regular expressions (regex) are powerful patterns used for matching, searching, and manipulating text. They provide a concise and flexible means for identifying strings of text, such as particular characters, words, or patterns of characters. Regex is supported in most programming languages and text editors.

Common Regex Patterns

\d - Matches any digit (0-9)
\w - Matches any word character (a-z, A-Z, 0-9, _)
\s - Matches any whitespace character
. - Matches any character except newline
^ and $ - Match start and end of string
*, +, ? - Quantifiers (0+, 1+, 0-1)

Use Cases

Form validation (email, phone, password)
Find and replace operations
Data extraction from text
Log file parsing
Input sanitization

Frequently Asked Questions

What is a regular expression (regex)?

A regular expression (regex or regexp) is a sequence of characters that defines a search pattern. It's used for string matching, validation, and text manipulation. Common uses include email validation, phone number formatting, and finding patterns in text.

What regex flags are supported?

This tool supports all JavaScript regex flags: g (global - find all matches), i (case insensitive), m (multiline - ^ and $ match line boundaries), s (dotAll - . matches newlines), u (unicode), and y (sticky).

How do I match exact words in regex?

To match exact words, use word boundaries: \bword\b. For example, \bcat\b matches 'cat' but not 'category' or 'educate'. The \b asserts a position between a word character and a non-word character.

What does the regex cheat sheet include?

The cheat sheet includes common patterns like . (any character), \d (digit), \w (word character), \s (whitespace), ^ (start of string), $ (end of string), * (0 or more), + (1 or more), ? (0 or 1), and character classes [abc].