Regex Memo
Regex syntax quick reference and common patterns, covering character classes, quantifiers, anchors, assertions, etc. 100% free, no signup, runs locally in your browser—nothing is uploaded to our servers.
Character Classes
[abc]Any of a, b, or c/[aeiou]/.test('a') → trueClick to copy[^abc]Not a, b, nor c/[^aeiou]/.test('b') → trueClick to copy[a-z]Character range a to z/[a-z]/.test('m') → trueClick to copy.Any character except newline/./.test('x') → trueClick to copy\dDigit [0-9]/\d/.test('5') → trueClick to copy\DNon-digit [^0-9]/\D/.test('a') → trueClick to copy\wWord character [a-zA-Z0-9_]/\w/.test('_') → trueClick to copy\WNon-word character/\W/.test('!') → trueClick to copy\sWhitespace/\s/.test(' ') → trueClick to copy\SNon-whitespace/\S/.test('a') → trueClick to copyQuantifiers
*0 or more/go*/.test('g') → trueClick to copy+1 or more/go+/.test('go') → trueClick to copy?0 or 1 (optional)/colou?r/.test('color') → trueClick to copy{n}Exactly n/a{3}/.test('aaa') → trueClick to copy{n,}n or more/a{2,}/.test('aaa') → trueClick to copy{n,m}Between n and m/a{2,4}/.test('aaa') → trueClick to copy*?0 or more (lazy)/a*?/.exec('aaa') → ''Click to copy+?1 or more (lazy)/a+?/.exec('aaa') → 'a'Click to copyAnchors
^Start of string/^hello/.test('hello world') → trueClick to copy$End of string/world$/.test('hello world') → trueClick to copy\bWord boundary/\bword\b/.test('a word b') → trueClick to copy\BNon-word boundary/\Bord\B/.test('word') → falseClick to copyGroups & Capturing
(abc)Capture group/(ab)c/.exec('abc')[1] → 'ab'Click to copy(?:abc)Non-capturing group/(?:ab)c/.exec('abc')[1] → undefinedClick to copy(?<name>abc)Named capture group/(?<w>ab)c/.exec('abc').groups.w → 'ab'Click to copy\1Backreference to group 1/(a)\1/.test('aa') → trueClick to copy$1Replacement reference'ab'.replace(/(a)/, '$1x') → 'axb'Click to copyLookaround Assertions
(?=abc)Positive lookahead/a(?=b)/.test('ab') → trueClick to copy(?!abc)Negative lookahead/a(?!b)/.test('ac') → trueClick to copy(?<=abc)Positive lookbehind/(?<=a)b/.test('ab') → trueClick to copy(?<!abc)Negative lookbehind/(?<!a)b/.test('cb') → trueClick to copyFlags
gGlobal — find all matches'aaa'.replace(/a/g, 'b') → 'bbb'Click to copyiCase-insensitive/a/i.test('A') → trueClick to copymMultiline (^/$ match line ends)/^b/m.test('a\nb') → trueClick to copysDotall (. matches newline)/a.b/s.test('a\nb') → trueClick to copyuUnicode/\u{1F600}/u.test('😀') → trueClick to copyySticky (match at lastIndex)/a/y.exec('aaa') → 'a' at 0Click to copyCommon Patterns
^[\w.-]+@[\w.-]+\.\w+$Email (basic)/^[\w.-]+@[\w.-]+\.\w+$/.test('a@b.com') → trueClick to copy^https?://[\S]+$URL (basic)/^https?:\/\/[\S]+$/.test('http://x') → trueClick to copy^\d{4}-\d{2}-\d{2}$Date YYYY-MM-DD/^\d{4}-\d{2}-\d{2}$/.test('2024-01-01') → trueClick to copy^#?([0-9a-fA-F]{3}|[0-9a-fA-F]{6})$Hex color/^#?([0-9a-fA-F]{3}|[0-9a-fA-F]{6})$/.test('#fff') → trueClick to copy^\d+$Integer only/^\d+$/.test('123') → trueClick to copy^-?\d+(\.\d+)?$Decimal number/^-?\d+(\.\d+)?$/.test('-3.14') → trueClick to copy^(?=.*[A-Z])(?=.*[a-z])(?=.*\d).{8,}$Strong password (8+ chars, upper, lower, digit)test('Abc12345') → trueClick to copy