Regex Cheatsheet

Awesome regex cheatsheet I found online. Often, I find myself re-learning regex syntax because I don’t use it often.

Expr	Usage
/hello/	looks for the string between the forward slashes (case-sensitive)
/hello/i	looks for the string between the forward slashes (case-insensitive)
/hello/g	looks for multiple occurrences of string between the forward slashes
/h.llo/	the ‘.’ matches any one character other than a new line character… matches ‘hello’, ‘hallo’ but not ‘h llo’
/h.*llo/	the “*” matches any character(s) zero or more times… matches “hello”, “heeeeeello”, “hllo”, “hwarwareallo”
/\d/	matches any digit
/\D/	matches any non-digit
/\w/	matches any word character (a-z, A-Z, 0-9, _)
/\W/	matches any non-word character
/\s/	matches any white space character (\r (carriage return),\n (new line), \t (tab), \f (form feed))
/\S/	matches any non-white space character
/[abcd]/	matches any character in square brackets
/[ch]at/	matches cat or hat
/[^abcd]/	matches anything except the characters in square brackets
/[a-z]/	matches all lowercase letters (a to z)
/[A-Z]/	matches all uppercase letters (A to Z)
/[0-9]/	matches all digits
/[a-zA-Z]/	matches all lowercase and uppercase letters
/[^a-zA-Z]/	matches non-letters
/[a-zA-Z0-9]/	matches all lowercase, uppercase letters and numbers
/(hello){4}/	matches “hellohellohellohello”
/hello{3}/	matches “hellooo” and “helloooo” but not “helloo”
/(hello){1,3}/	matches “hello” that occur between 1 and 3 times (inclusive)
/(hello){3,}/	matches “hello” that occur atleast 3 times
/ab*c/	matches zero or more repetitions of “b” (matches “abc”, “abbbbc”, “ac”)
/ab+c/	matches one or more repetitions of “b” (matches “abc”, “abbbbc”, but not “ac”)
/^/	matches beginning of a line
/$/	matches end of a line
/(hard)?work/	matches “work” or “hardwork”
/(?:hard)?work/	matches “work” or “hardwork” but is a non-capturing group
/i am a (cat|dog|whale) person/	matches “i am a cat person”, “i am a dog person” and “i am a whale person”
/z(?=a)/	positive lookahead… matches the “z” before the “a” in pizza but not the first “z”
/z(?!a)/	negative lookahead… matches the first “z” but not the “z” before the “a”
/(?<=[aeiou])\w/	positive lookbehind… matches any word character that is preceded by a vowel
/(?<![aeiou])\w/	negative lookbehind… matches any word character that is not preceded by a vowel

Copied from: https://ihateregex.io/cheatsheet/