Searching for patterns
/everything between slashes/- case sensitive by default
- Metacharacters have a meaning. If you need to match a metacharacter, you have to
\escape them in most cases[,{,(,),\,^,$,.,|,?,*,+
- Engine is greedy, will always match as much as possible by default
- parentheses capture groups
Validate an email address
/\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
Validate a hex
/^#([a-f\d]{3}){1,2}$/i
A 6+ letter password with at least: one number, one letter and one symbol
/^(?=.*\d)(?=.*[a-z])(?=.*[\W_]).{6,}$/i
Any number that's NOT divisible by 50
/\b(?!\d+[50]0)\d+\b/
Anything that doesn't contain "foo"
/^(?!.*foo).+$/
A YouTube ID
/(?:youtube\.com\/(?:[^\/]+\/.+\/|(?:v|e(?:mbed)?)\/|.*[?&]v=)|youtu\.be\/)([^"&?\/ ]{11})/i
[abc] // A single character of: a, b, or c
[^abc] // Any single character except: a, b, or c
[a-z] // Any single character in the range a-z
[a-zA-Z] // Any single character in the range a-z or A-Z
^ // Start of line
$ // End of line
\A // Start of string
\z // End of string
. // Any single character
\s // Any whitespace character
\S // Any non-whitespace character
\d // Any digit
\D // Any non-digit
\w // Any word character (letter, number, underscore)
\W // Any non-word character
\b // Any word boundary
(...) // Capture everything enclosed
(a|b) // a or b
a? // Zero or one of a
a* // Zero or more of a
a+ // One or more of a
a{3} // Exactly 3 of a
a{3,} // 3 or more of a
a{3,6} // Between 3 and 6 of a