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Regex Cheatsheet

Anchors, character classes, quantifiers, flags, and real-world regex patterns you can paste into your next search.

Reference index

Search patterns

Anchors and Boundaries Character Classes and Groups Quantifiers Lookarounds and References Copy-ready Patterns

Regex tester

Validate patterns against sample text before deployment.

PatternFlagsSample textReplacement (optional)

Compiled as /^\w+$/g

Matches: 0

Anchors and Boundaries

Control where matches begin and end.

Pattern	Meaning	Usage
`^`	Start of string or line	Anchor both ends for strict validation.
`$`	End of string or line	Useful for full-string matches.
`\b / \B`	Word boundary / non-boundary	Match standalone keywords.
`\A / \Z`	Absolute start / end	Some engines support these outside JS.

Character Classes and Groups

Build expressive token classes.

Pattern	Meaning	Usage
`.`	Any char except newline	Use dotall (s) to include newlines.
`[abc]`	Character set	Use ranges such as [a-zA-Z].
`\d \w \s`	Digit, word char, whitespace	Uppercase forms negate classes.
`(?:...)`	Non-capturing group	Groups without backreferences.

Quantifiers

Define repetition counts.

Pattern	Meaning	Usage
`*`	0 or more	Use *? for lazy matching.
`+`	1 or more	Required repeated token.
`?`	0 or 1	Optional token.
`{min,max}`	Explicit bounds	Example: {8,} for minimum length.

Lookarounds and References

Assert context without consuming characters.

Pattern	Meaning	Usage
`(?=...)`	Positive lookahead	Ensure next pattern exists.
`(?!...)`	Negative lookahead	Ensure next pattern does not exist.
`(?<=...)`	Positive lookbehind	Match text preceded by pattern.
`\1 \2`	Backreferences	Reuse captured groups.

Copy-ready Patterns

Common starter expressions.

Pattern	Meaning	Usage
`^[a-z0-9_-]{3,16}$`	Username (3-16 chars)	Allows letters, digits, underscore, hyphen.
`^\+?[0-9\s-]{7,}$`	Flexible phone	Optional plus, spaces, dashes.
`^[\w.-]+@[\w.-]+\.[a-z]{2,}$`	Email-like string	Lightweight client-side validation.
`^https?:\/\/[\w.-]+`	HTTP/HTTPS URL	Fast scheme + domain check.

How to use this tool

Browse sectioned regex references for anchors, classes, quantifiers, and lookarounds.
Use search to filter patterns by syntax, meaning, or practical usage tips.
Validate expressions in the inline tester and copy patterns or replacement output.

Reference scope

Includes quick reminders for common regex operators and boundary behavior.
Provides copy-ready starter patterns for usernames, email-like values, and URLs.
Pairs syntax with plain-language meaning to speed up implementation.

Usage notes

Treat included examples as starters and tighten them for your exact requirements.
Confirm behavior with representative real-world test input before release.
Different regex engines vary; validate syntax when targeting non-JS runtimes.

FAQ

Is this cheatsheet JavaScript-focused?: Yes. The inline tester compiles patterns using JavaScript RegExp in the browser.
Can I copy patterns directly?: Yes. Each row includes a copy action, plus replacement output can be copied from the tester.
Are these patterns production-ready?: They are useful starting points; validate and harden them for your specific data rules.

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Reference index

Regex tester

Anchors and Boundaries

Character Classes and Groups

Quantifiers

Lookarounds and References

Copy-ready Patterns

How to use this tool

Reference scope

Usage notes

FAQ

More like this

Reference index

Regex tester

Anchors and Boundaries

Character Classes and Groups

Quantifiers

Lookarounds and References

Copy-ready Patterns