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 = /[^\w](?<!->)(trans|trans_choice|Lang::get|Lang::choice|Lang::trans|Lang::transChoice|@lang|@choice|__)\s*\(\s*((?<![\\])['"])((?:.(?!(?<![\\])\2))*.?)\2\s*[,\)]/g; // Alternative syntax using RegExp constructor // const regex = new RegExp('[^\\w](?<!->)(trans|trans_choice|Lang::get|Lang::choice|Lang::trans|Lang::transChoice|@lang|@choice|__)\\s*\\(\\s*((?<![\\\\])[\'"])((?:.(?!(?<![\\\\])\\2))*.?)\\2\\s*[,\\)]', 'g') const str = `Should match variations on method: trans('a.b'); trans_choice('a.b') Lang::get('a.b'); Lang::choice('a.b', 1); Lang::trans('a.b'); Lang::transChoice('a.b', 2); @lang('language.line') @choice('language.line', 1); __('a.b') Should match variations of contained string trans('key'); // No group, so JSON style __('Json string') trans('a.b'); trans('a.b.c'); trans('a_b.c-d'); trans('a.b!'); trans('a.translate me!'); trans('a.über~'); trans("app.i'm"); // contained quote of different type trans('app."ok"'); trans('with contained " quotes'); trans('with an escaped \\' quote') trans('with a double \\\\') Should match additional variables and whitespace trans('a.b', [1,2]); trans ( ' with whitespace ' , \$var) Typical use cases (trans ( 'lang.line')); <span>@lang('lang.line')</span> Should not match: trans(\$var); // No quotes trans(); // Nothing anytrans('group.key'); // not the method we need 1trans('lang.file'); // not the method _trans('lang.file'); // not the method ->trans('lang.line'); trans(\\'why do we have an escaped quote here?\\') trans('with a triple \\\\\\') <-- fail! trans('lang.line' . \$middle); // concatenated vars trans('lang.line' . \$middle . '.ending'); // concatenated vars ___('hello') // not the method we need `; // 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