Regular Expressions Cheat Sheet

A regular expression is a sequence of characters defining a search expression, used for pattern matching in strings

References

Refiddle - an online regex utility, similar to JSFiddle

Characters

Anchors

• ^ - start of line
• \A - start of string
• $ - End of Line
• \Z - End of string
• \b - Word boundary
• \B - Not word boundary
• \< - Start of word
• \> - End of word

Character Classes

• \c - Control character
• \s - White space
• \S - Not white space
• \d - Digit
• \D - Not digit
• \w - word
• \W - Not word

Quantifiers

• * - 0 or more
• *? - 0 or more, ungreedy
• + - 1 or more
• +? - 1 or more, ungreedy
• ? - 0 or 1
• ?? - 0 or 1, ungreedy
• {3} - exactly 3
• {3,} - 3 or more
• {3,5} - 3, 4 or 5
• {3,5}? - 3, 4 or 5, ungreedy

Ranges

• . - Any character except new line(\n)
• (a|b) - a or b
• (...) - group
• (?:...) - passive group
• [abc] - Range (a or b or c)
• [^abc] - Not a or b or c
• [a-q] - Letter between a and q
• [A-Q] - Upper case letter between A and Q
• [0-7] - Digit between 0 and 7

Pattern Modifiers

• g - Global match
• i - Case-insensitive
• m - Multiple lines
• s - Treat string as single line
• x - Allow comments and whitespace in pattern
• e - Evaluate replacement
• U - Ungreedy pattern

Special Characters

• \ - Escape character
• \n - New Line
• \r - Carriage return
• \t - Tab
• \v - Vertical tab
• \f - Form feed
• \a - Alarm
• `[\b] - Backspace
• \e - Escape

Examples

Phone Number

/[0-9]{3}-[0-9]{3}-[0-9]{4}/

123-456-9000 - match
456-9000 - no match
1234569000 - no match

Email

/[^\s@]+@[^\s@]+\.[^\s@]+/

brian@gmail.com - match
briangmail.com - no match
brian.vp@gmail.com - match
brian@@gmail.com - no match

Date

/\d{1,2}\/\d{1,2}/\d{2,4}/

11/8/1980 - match
11/8/80 - match
118/80 - no match
111/8/80 - no match