Regex Cheat Sheet (Javascript Edition)

================== REGEXP CHEAT SHEET ================== By @geochronology - https://github.com/geochronology Methods ------- ## test() Checks if regex matches var Syntax: regex.text(var) `myRegex.test(myString)` ## match() Returns array of pattern matches * Without /g, only returns first match * With /g, returns all matches Syntax: var.match(regex) `/regex/.test('string');` ## replace() Swaps occurences of a regex with something else * With plain text: wrongText.replace(silverRegex, "blue"); // returns "The sky is blue" * With capture groups: "Code Camp".replace(/(\w+)\s(\w+)/, '$2 $1'); // returns "Camp Code" Flags ----- ## /i Ignore case ## /g Global match Shorthands --------------- ## \w Equivalent to [A-Za-z0-9_] `/\w+/` // returns one or more alphanumeric char ## \W Excludes all alphanumeric chars (opposite of \w) ## \d Any digit. Equivalent to [0-9] ## \D Any non-digit. Equivalent to [^0-9] ## \s Any whitespace. Equivalent to [ \r\t\f\n\v] ## \S Any non-whitespace. Equivalent to [^ \r\t\f\n\v] Character Groups --------------------- ## [...] Character group. Checks to see if it matches one of the characters in the group. `/h[au]m` ## [a-z] Character range. Checks if it matches any character within the range. ## [1-6] Number range. Checks if it matches any number within the range. ## [a-z0-9] Letter and number range. Checks if it matches either of the ranges. ## [^abcd] Negated character set. Specifies characters you dont want to match. ## (abc|def) Check if one of the enclosed patterns occurs `/che(ese|ss)/` // matches "cheese" or "chess" ## (?:..)? Optional group. Matches the enclosed pattern 0 or 1 time(s). `/^(?:1 )?\(\d{3}\) \d{3}-\d{4}$/` // matches "1 (555) 555-5555" and "(555) 555-5555" Symbols ------------ ## . Wildcard character. Matches any one character. `/hu./` ## + Match one or more occurence. Identifies characters that repeat themselves. `/a+/` ## * Match a character that occurs 0 or more times. With one char: `/fi*/`: "fig" // returns "fi" "foot" // returns "f" "leslie" // returns null With char range: `/f[aeiou]*g/` ## ^ Starts with ## $ Ends with Patterns ------------- ## /^moose/ Searches for pattern at the beginning of strings ## /moose$/ Searches for pattern at end of string ## /(...)\1/ Creates a capture group of stuff inside the parens Each number refers to each subsequent capture group created Operators -------------- ## | (or operator) Match one of 2 or more options. /moose|notMoose/ /moose|notMoose|possiblyMoose/ ## ? (lazy matching) Returns the shortest possible matching string. (Default is longest possible.) "plumply": `/p[a-z]*l/` // returns "plumpl" `/p[a-z]*?l/` // returns "pl" ## ? (optional character) Says preceding character is optional. (Useful for British english) `/colou?r/` ## {x, y} (quantity specifiers) Specifies range of times something gets repeated (min, max) * Range: `/a{3,5}h/` * Lower only: `/a{3,}h/` * Exact: `/a{3}h/` ## (?=...), (?!...) (positive/negative lookaheads) Looks ahead to see if pattern is/isnt there `(?=bucket)` // looks for bucket `(?!bucket)` // looks not for bucket