Common Regex Patterns

[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}

Matches most email address formats

https?://(?:[-\w.])+(?:\:[0-9]+)?(?:/(?:[\w/_.])*)?(?:\?(?:[\w&=%.])*)?(?:\#(?:[\w.])*)?

Matches HTTP and HTTPS URLs

^$?([0-9]{3})$?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$

Matches US phone number formats

^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$

Matches IPv4 addresses

^(0[1-9]|1[0-2])\/(0[1-9]|[12][0-9]|3[01])\/\d{4}$

Matches MM/DD/YYYY date format

^#?([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$

Matches hex color codes

Regex Flags Explained

g (global): Find all matches, not just the first one

i (ignore case): Case-insensitive matching

m (multiline): ^ and $ match start/end of lines, not just string

s (dotall): . matches newline characters

u (unicode): Enable full Unicode support

y (sticky): Match from exact position in string

. Matches any character except newline

* Matches 0 or more of the preceding character

+ Matches 1 or more of the preceding character

? Matches 0 or 1 of the preceding character

^ Matches start of string

$ Matches end of string

[] Character class - matches any character inside

() Capturing group

| Alternation (OR)

\d Matches any digit (0-9)

\w Matches any word character (a-z, A-Z, 0-9, _)

\s Matches any whitespace character