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

/
/
gmi

Test String

Substitution

Processing...

Code Generator

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "(\\([\\w\\s].*[\\w\\s]\\)|\\(\\)) =>"; final String string = "var MODULE = ((my, $, undefined) => {\n\n" + " console.log('EXECUTION FROM LEGACY APP START ===>');\n\n" + " // if private var defined in my module, use that\n" + " // else create a private var\n" + " var _private = my._private = my._private || {},\n" + " _seal = my._seal = function seal(seal) {\n" + " if (!seal) {\n" + " return;\n" + " }\n\n" + " delete my._private;\n" + " delete my._seal;\n" + " console.log('SEALED');\n" + " },\n" + " _unseal = my._unseal = function unseal(unseal) {\n" + " if (!unseal) {\n" + " return;\n" + " }\n\n" + " my._seal = _seal;\n" + " my._private = _private;\n" + " console.log('UNSEALED');\n" + " };\n\n" + " var name = 'Tonny Frank';\n" + " _private.name = 'This is a private name: ' + name;\n\n" + " _private.reverse = function reverse(str) {\n" + " return str.split('').reverse().join('');\n" + " };\n\n" + " if ($ === undefined) {\n" + " console.log('jQuery not defined');\n" + " return;\n" + " }\n\n" + " $(() => {\n" + " var $h1 = $('.card').children('h1');\n" + " $h1.html(_private.reverse($h1.html()));\n" + " });\n\n" + " console.log(my);\n" + " my.myMethod = () => {\n" + " console.log('MODULE myMethod Executed');\n" + " $('.name').html('Abhisek ...');\n" + " $('button').click(function (ev) {\n" + " ev.preventDefault();\n" + " console.log(this);\n" + " $(this).html('Damn!');\n" + " });\n" + " };\n\n" + " console.log('EXECUTION FROM LEGACY APP END <===');\n\n" + " return my;\n" + "})(MODULE || {}, this.jQuery);\n"; final String subst = "function $1"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | Pattern.CASE_INSENSITIVE); final Matcher matcher = pattern.matcher(string); // The substituted value will be contained in the result variable final String result = matcher.replaceAll(subst); System.out.println("Substitution result: " + result); } }

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 Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html