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

re = /(?:(?:(?:(?:var|let)[ \t]+)?([\w.\-]+)[ \t]*[:=]|[(!])[ \t]*)function(?:[ \t]+([\w.\-]+))?[ \t]*\([^)]*\)/m str = '!function(){}() // test1 !function test2(){}() // test2 (function(){})() // test3 (function test4(){})() // test4 test5 = function(){} // test5 test6 = function _test6(){} // test6 let test7 = function(){} // test7 let test8 = function _test8(){} // test8 var test9 = function(){} // test8 var test10 = function _test10(){} // test10 myfunc(function(){}) // test11 myfunc(function test12(){}) // test12 let myobj = {test13 : function(){}} // test13 let myobj = {test14 : function _test14(){}} // test14 var myobj = {test15 : function(){}} // test15 var myobj = {test16 : function _test16(){}} // test16 ' # Print the match result str.scan(re) do |match| puts match.to_s end

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 Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html