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

Code Generator

Language

Generated Code

const regex = /^=\?UTF-8\?Q\?(?=.*=E.=..=..)(?=.*[^=]*)?.*\?=/gmi; // Alternative syntax using RegExp constructor // const regex = new RegExp('^=\\?UTF-8\\?Q\\?(?=.*=E.=..=..)(?=.*[^=]*)?.*\\?=', 'gmi') const str = `=?UTF-8?q?=E5=8F=A3=E5=BA=A7=E6=83=85=E5=A0=B1=E7=A2=BA=E8=AA=8D=E3=81=AE?= =?UTF-8?q?ANA=E3=83=9E=E3=82=A4=E3=83=AC=E3=83=BC=E3=82=B8=E3=82=AF?= =?UTF-8?q?=E3=81=84=E3=80=91ANA=E3=83=9E=E3=82=A4=E3=83=AC=E3=83=BC?= =?UTF-8?q?=E3=80=90=E3=81=94=E7=A2=BA=E8=AA=8D=E3=81=8F=E3=81=A0=E3=81=95?= =?UTF-8?q?=E3=81=84=E3=80=91ANA=E3=83=9E=E3=82=A4=E3=83=AC=E3=83=BC?= =?UTF-8?q?=E3=82=B8=E3=82=AF=E3=83=A9=E3=83=96=EF=BC=9A=E6=9C=AA=E5=8A=A0?= =?UTF-8?q?=E7=AE=97=E3=83=9E=E3=82=A4=E3=83=AB=E3=81=AE=E6=89=8B=E7=B6=9A?= =?UTF-8?q?=E3=81=8D=E6=A1=88=E5=86=85=EF=BC=88=E3=83=A1=E3=83=BC=E3=83=AB?= =?UTF-8?q?=E7=95=AA=E5=8F=B7:CF-FC-01194167741=EF=BC=89?= =?UTF-8?q?=E5=8F=A3=E5=BA=A7=E5=8F=96=E5=BC=95=E5=88=B6=E9=99=90=E3=81=AE?= =?UTF-8?q?=E3=81=94=E6=A1=88=E5=86=85=EF=BC=9A=E3=82=AA=E3=83=AA=E3=82=B3?= =?UTF-8?q?=E6=83=85=E5=A0=B1=E3=82=92=E6=9B=B4=E6=96=B0=E3=81=97=E3=81=A6?= =?UTF-8?q?=E3=81=8F=E3=81=A0=E3=81=95=E3=81=84=E2=97=89PU-89581655388?= =?UTF-8?q?hello?= `; // 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