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

r"
"
gm

Test String

Code Generator

Language

Generated Code

const regex = new RegExp('^[\\d.]+\\/\\d\\d\\S*', 'gm') const str = `0.0.0.0/0 *[OSPF/150] 5w2d 19:06:26, metric 24, tag 100 to 10.239.248.129 via ae101.0 > to 10.239.248.137 via ae102.0 1.1.21.0/30 *[OSPF/10] 5w2d 19:06:26, metric 23 > to 10.239.248.129 via ae101.0 to 10.239.248.137 via ae102.0 [BGP/170] 10w3d 08:00:01, localpref 260, from 189.40.251.20 AS path: 17379 I, validation-state: unverified > to 10.239.248.129 via ae101.0, Push 16151 to 10.239.248.137 via ae102.0, Push 16109 [BGP/170] 10w3d 08:00:54, localpref 260, from 189.40.251.21 AS path: 17379 I, validation-state: unverified > to 10.239.248.129 via ae101.0, Push 16151 to 10.239.248.137 via ae102.0, Push 16109 1.1.21.4/30 *[OSPF/10] 5w2d 19:06:26, metric 23 to 10.239.248.129 via ae101.0 > to 10.239.248.137 via ae102.0 [BGP/170] 10w3d 07:57:12, MED 120, localpref 100, from 189.40.251.21 AS path: ?, validation-state: unverified > to 10.239.248.129 via ae101.0 [BGP/170] 10w3d 07:56:39, MED 120, localpref 100, from 189.40.251.20 AS path: ?, validation-state: unverified `; // 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