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

/
/
g

Test String

Code Generator

Language

Generated Code

const regex = /([^\s=]+)=('?)("?)([^>"']*)\2\3/g; // Alternative syntax using RegExp constructor // const regex = new RegExp('([^\\s=]+)=(\'?)("?)([^>"\']*)\\2\\3', 'g') const str = ` style="width: 462px;" src='data:image/png;base64,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' data-filename="Screenshot from 2016-02-09 21:54:47.png" <tr><td><A HREF="brackets.html" TARGET="_top">Capturing group</A></td> <td><TT>(regex)</TT></td> <td>Parentheses group the regex between them. They capture the text matched by the regex inside them into a numbered group that can be reused with a numbered backreference. They allow you to apply regex operators to the entire grouped regex.</td> <td><TT CLASS=code><SPAN CLASS="regexnest1">(</SPAN><SPAN CLASS="regexplain">abc</SPAN><SPAN CLASS="regexnest1">)</SPAN><SPAN CLASS="regexspecial">{3}</SPAN></TT> matches <TT CLASS=match>abcabcabc</TT>. First group matches <TT CLASS=match>abc</TT>.</td> <td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>ECMA<br>extended<br>egrep<br>awk</td><td class=yes>YES</td><td>no</td><td class=yes>YES</td><td>no</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td></tr> <tr><td><A HREF="brackets.html" TARGET="_top">Capturing group</A></td> <td><TT>\\(regex\\)</TT></td> <td>Escaped parentheses group the regex between them. They capture the text matched by the regex inside them into a numbered group that can be reused with a numbered backreference. They allow you to apply regex operators to the entire grouped regex.</td> <td><TT CLASS=code><SPAN CLASS="regexnest1">\\(</SPAN><SPAN CLASS="regexplain">abc</SPAN><SPAN CLASS="regexnest1">\\)</SPAN><SPAN CLASS="regexplain">{3}</SPAN></TT> matches <TT CLASS=match>abcabcabc</TT>. First group matches <TT CLASS=match>abc</TT>.</td> <td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td class=yes>basic<br>grep</td><td>no</td><td class=yes>YES</td><td>no</td><td class=yes>YES</td><td>no</td><td>no</td><td>no</td><td>no</td></tr> <tr><td><A HREF="brackets.html" TARGET="_top">Non-capturing group</A></td> `; // 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