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
Processing...

Test String

Code Generator

Language

Generated Code

const regex = /[0-9]+:[0-9]+:?\s*(?:\[?warning\]?|\[?error\]?)|(?:::warning file=|::error file=)/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('[0-9]+:[0-9]+:?\\s*(?:\\[?warning\\]?|\\[?error\\]?)|(?:::warning file=|::error file=)', 'gm') const str = `PARSABLE [yamllint] TEST FILES/yaml/yml_bad_1.yml - ERROR - 2 error(s) --Error detail: TEST FILES/yaml/yml_bad_1.yml:0:1: [warning] missing document start "---" (document-start) TEST FILES/yaml/yml_bad_1.yml:11:16: error] syntax error: mapping values are not allowed here (syntax) [yamllint] TEST FILES/yaml/yml_bad_2.yml - ERROR - 2 error(s) --Error detail: TEST FILES/yaml/yml_bad_2.yml:10:1: [warning] missing document start "---" (document-start) TEST FILES/yaml/yml_bad_2.yml:11:1116: [error] syntax error: mapping values are not allowed here (syntax) [yamllint] TEST FILES/yaml_schema/bad/action.yml - ERROR - 2 error(s) --Error detail: TEST FILES/yaml_schema/bad/action.yml:1:1: [warning] missing document start "---" (document-start) TEST FILES/yaml_schema/bad/action.yml:2:1: [error] too many blank lines (1 > 0) (empty-lines) COLORED [Tap Reporter] Generated TAP report: /tmp/lint/megalinter-reports/tap/mega-linter-YAML_PRETTIER.tap ❌ Linted [YAML] files with [yamllint]: Found 6 error(s) - (1.36s) - Using [yamllint v1.35.1] https://megalinter.io/All_Fixes_Together/descriptors/yaml_yamllint - MegaLinter key: [YAML_YAMLLINT] - Rules config: [/_Pipelines/LinterRules/.yamllint.yml] - Number of files analyzed: [10] [yamllint] TEST FILES/yaml/yml_bad_1.yml - ERROR - 2 error(s) --Error detail: TEST FILES/yaml/yml_bad_1.yml 10:1 warning missing document start "---" (document-start) 11:16 error syntax error: mapping values are not allowed here (syntax) [yamllint] TEST FILES/yaml/yml_bad_2.yml - ERROR - 2 error(s) --Error detail: TEST FILES/yaml/yml_bad_2.yml 10:1 warning missing document start "---" (document-start) 11:16 error syntax error: mapping values are not allowed here (syntax) STANDARD ❌ Linted [YAML] files with [yamllint]: Found 6 error(s) - (1.23s) - Using [yamllint v1.35.1] https://megalinter.io/All_Fixes_Together/descriptors/yaml_yamllint - MegaLinter key: [YAML_YAMLLINT] - Rules config: [/_Pipelines/LinterRules/.yamllint.yml] - Number of files analyzed: [10] [yamllint] TEST FILES/yaml/yml_bad_1.yml - ERROR - 2 error(s) --Error detail: TEST FILES/yaml/yml_bad_1.yml 10:1 warning missing document start "---" (document-start) 11:16 error syntax error: mapping values are not allowed here (syntax) [yamllint] TEST FILES/yaml/yml_bad_2.yml - ERROR - 2 error(s) --Error detail: TEST FILES/yaml/yml_bad_2.yml 10:1 warning missing document start "---" (document-start) 11:16 error syntax error: mapping values are not allowed here (syntax) [yamllint] TEST FILES/yaml_schema/bad/action.yml - ERROR - 2 error(s) --Error detail: TEST FILES/yaml_schema/bad/action.yml 1:1 warning missing document start "---" (document-start) 2:1 error too many blank lines (1 > 0) (empty-lines) ❌ Linted [YAML] files with [yamllint]: Found 3 error(s) - (1.54s) - Using [yamllint v1.35.1] https://megalinter.io/All_Fixes_Together/descriptors/yaml_yamllint - MegaLinter key: [YAML_YAMLLINT] - Rules config: [/_Pipelines/LinterRules/.yamllint.yml] - Number of files analyzed: [10] [yamllint] TEST FILES/yaml/yml_bad_1.yml - ERROR - 1 error(s) --Error detail: ::group::TEST FILES/yaml/yml_bad_1.yml ::warning file=TEST FILES/yaml/yml_bad_1.yml,line=10,col=1::10:1 [document-start] missing document start "---" ::error file=TEST FILES/yaml/yml_bad_1.yml,line=11,col=16::11:16 syntax error: mapping values are not allowed here (syntax) ::endgroup:: [yamllint] TEST FILES/yaml/yml_bad_2.yml - ERROR - 1 error(s) --Error detail: ::group::TEST FILES/yaml/yml_bad_2.yml ::warning file=TEST FILES/yaml/yml_bad_2.yml,line=10,col=1::10:1 [document-start] missing document start "---" Warning: 1:1 [document-start] missing document start "---" Warning: 13:14 [truthy] truthy value should be one of [false, true] Warning: 17:14 [truthy] truthy value should be one of [false, true] Warning: 21:14 [truthy] truthy value should be one of [false, true] Warning: 25:14 [truthy] truthy value should be one of [false, true] Warning: 37:14 [truthy] truthy value should be one of [false, true] Warning: 56:2 [comments] missing starting space in comment Warning: 57:2 [comments] missing starting space in comment Warning: 58:2 [comments] missing starting space in comment Warning: 59:2 [comments] missing starting space in comment Warning: 60:2 [comments] missing starting space in comment Error: 77:1 [empty-lines] too many blank lines (3 > 2) Error: 86:1 [empty-lines] too many blank lines (4 > 2)`; // 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