Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
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

/
/
img

Test String

Substitution

Processing...

Code Generator

Language

Generated Code

const regex = /(?:<TD CLASS="label")(?:.*>)(?s)(?<lbl>.*?)(?:<\/TD>).*?(?:<TD NOWRAP>).*?(?:type=)"(?<type>[^"]*)".*?(?:name=)"(?<name>[^"]*)".(?:title=)"(?<title>[^"]*)".*?(?:id=)"(?<id>[^"]*)".*?(?:value=)"(?<value>[^"]*)".*?(?:size=)"(?<size>[^"]*)".*?(?:maxlength=)"(?<maxlength>[^"]*)"*.*?<\/TD>$/img; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?:<TD CLASS="label")(?:.*>)(?s)(?<lbl>.*?)(?:<\\\/TD>).*?(?:<TD NOWRAP>).*?(?:type=)"(?<type>[^"]*)".*?(?:name=)"(?<name>[^"]*)".(?:title=)"(?<title>[^"]*)".*?(?:id=)"(?<id>[^"]*)".*?(?:value=)"(?<value>[^"]*)".*?(?:size=)"(?<size>[^"]*)".*?(?:maxlength=)"(?<maxlength>[^"]*)"*.*?<\\\/TD>$', 'img') const str = `<tr> <TD CLASS="label" NOWRAP VALIGN="MIDDLE"> &nbsp;Average_No_of_Direct_Employees: &nbsp; </TD> <TD NOWRAP> <INPUT CLASS="valueEditable" TYPE="text" NAME="_1_1_10_1" TITLE="Average_No_of_Direct_Employees" ID="_1_1_10_1" VALUE="[LL_FormTag_1_1_10_1 /]" SIZE="20" MAXLENGTH="20" ONCHANGE="markDirty();"> </TD> </TR> <!-- End File: datefield.html (End - _1_1_9_1) --> </TD> </TR> <TR CLASS="horizontalCellDivider" > <TD CLASS="labelHorizontalDivider" COLSPAN="1"><IMG HEIGHT="1" ALT="" SRC="/img/spacer.gif" WIDTH="1" BORDER="0"></TD> <TD CLASS="valueHorizontalDivider" COLSPAN="1"><IMG HEIGHT="1" ALT="" SRC="/img/tbl-divider-hor.gif" WIDTH="3" BORDER="0"></TD> </TR> <TR> <TD CLASS="label" NOWRAP VALIGN="MIDDLE"> &nbsp;Average_No_of_Direct_Employees: &nbsp; </TD> <TD NOWRAP> <INPUT CLASS="valueEditable" TYPE="text" NAME="_1_1_10_1" TITLE="Average_No_of_Direct_Employees" ID="_1_1_10_1" VALUE="[LL_FormTag_1_1_10_1 /]" SIZE="20" MAXLENGTH="20" ONCHANGE="markDirty();"> </TD> </TR> <TR CLASS="horizontalCellDivider" > <TD CLASS="labelHorizontalDivider" COLSPAN="1"><IMG HEIGHT="1" ALT="" SRC="/img/spacer.gif" WIDTH="1" BORDER="0"></TD> <TD CLASS="valueHorizontalDivider" COLSPAN="1"><IMG HEIGHT="1" ALT="" SRC="/img/tbl-divider-hor.gif" WIDTH="3" BORDER="0"></TD> </TR> <TR> <TD CLASS="label" NOWRAP VALIGN="MIDDLE"> &nbsp;Average_No_of_SubContractors_on-site: &nbsp; </TD> <TD NOWRAP> <INPUT CLASS="valueEditable" TYPE="text" NAME="_1_1_11_1" TITLE="Average_No_of_SubContractors_on-site" ID="_1_1_11_1" VALUE="[LL_FormTag_1_1_11_1 /]" SIZE="20" MAXLENGTH="20" ONCHANGE="markDirty();"> </TD> </TR> <TR CLASS="horizontalCellDivider" > <TD CLASS="labelHorizontalDivider" COLSPAN="1"><IMG HEIGHT="1" ALT="" SRC="/img/spacer.gif" WIDTH="1" BORDER="0"></TD> <TD CLASS="valueHorizontalDivider" COLSPAN="1"><IMG HEIGHT="1" ALT="" SRC="/img/tbl-divider-hor.gif" WIDTH="3" BORDER="0"></TD> </TR> <TR>`; const subst = `<div class="medium-6 columns">\n <label>${lbl} <!--### INPUT EXAMPLE ### -->\n <input type="${type} <" NAME="${name}" TITLE="${title}" ID="${id}" VALUE="${value}" SIZE="${size}" MAXLENGTH="${maxlength}" ONCHANGE="markDirty();>\n </label>\n</div>`; // The substituted value will be contained in the result variable const result = str.replace(regex, subst); console.log('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 JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions