Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

/
/
gm

Test String

Code Generator

Language

Generated Code

const regex = /^(0|[1-9]+[0-9]*) (@[^@]+@ |)([A-Za-z0-9_]+)( [^\n\r]*|)$/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(0|[1-9]+[0-9]*) (@[^@]+@ |)([A-Za-z0-9_]+)( [^\\n\\r]*|)$', 'gm') const str = `0 @N1@ NOTE Lorem ipsum dolor sit amet 0 HEAD 1 SOUR FTM 2 VERS 22.2.6.950 1 DEST FTM 1 DATE 31 MAR 2017 1 CHAR UTF-8 3 _LINK http://www.facebook.com/1247584965 2 SOUR @S122@ 3 PAGE Facebook update - David Hatch - 6/5/2013 3 _LINK http://www.facebook.com/1247584965 1 RESI 2 DATE BET 1935 AND 1993 2 PLAC San Francisco, California, USA 1 RESI 2 DATE 1994 2 PLAC San Francisco, California, USA 2 SOUR @S605@ 3 DATA 4 TEXT Birth date: 20 Sep 1966 Birth place: Residence date: 1994 5 CONC Residence place: San Francisco, CA 1 RESI 106 Oakcrest Rd 2 DATE 26 MAR 2017 2 PLAC San Anselmo, Marin, California, USA 1 FAMS @F500@ 1 FAMC @F656@ 0 @I923@ INDI 1 NAME Vincent /Crilley/ 1 SEX M 1 FAMS @F254@ 0 @I5899@ INDI 1 NAME Marjorie Edna /Footitt/ 2 SOUR @S506@ 2 SOUR @S176@ 2 SOUR @S168@ 2 SOUR @S624@ 3 DATA 4 TEXT Residence date: Residence place: USA 2 SOUR @S115@ 3 PAGE Year: 1940; Census Place: St Paul, Ramsey, Minnesota; Roll: T627_1996; 4 CONC Page: 11A; Enumeration District: 90-73. 3 DATA 4 _TEXT Birth date: abt 1918 Birth place: North Dakota Residence date: 1 5 CONC Apr 1940 Residence place: St Paul, Ramsey, Minnesota, United States 2 SOUR @S607@ 3 PAGE Year: 1920; Census Place: Carrington, Foster, North Dakota; Roll: 4 CONC T625_1334; Page: 13B; Enumeration District: 117; Image: . 3 DATA`; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; while ((m = regex.exec(str)) !== null) { // This is necessary to avoid infinite loops with zero-width matches if (m.index === regex.lastIndex) { regex.lastIndex++; } // The result can be accessed through the `m`-variable. m.forEach((match, groupIndex) => { console.log(`Found match, group ${groupIndex}: ${match}`); }); }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions