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

/
/
gm

Test String

Code Generator

Language

Generated Code

const regex = /ec2-(?:25[0-5]|2[0-4]\d|[0-1]?\d{1,2})(?:-(?:25[0-5]|2[0-4]\d|[0-1]?\d{1,2})){3}\.(?:eu|us|af|ap|ca|me|sa)-(?:west|central|south|north|(?:south|north)?east)-[1-9]{1,1}\.compute\.amazonaws\.com/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('ec2-(?:25[0-5]|2[0-4]\\d|[0-1]?\\d{1,2})(?:-(?:25[0-5]|2[0-4]\\d|[0-1]?\\d{1,2})){3}\\.(?:eu|us|af|ap|ca|me|sa)-(?:west|central|south|north|(?:south|north)?east)-[1-9]{1,1}\\.compute\\.amazonaws\\.com', 'gm') const str = `ec2-54-189-171-120.us-east-1.compute.amazonaws.com ec2-35-158-116-105.us-east-2.compute.amazonaws.com ec2-13-210-58-232.us-west-1.compute.amazonaws.com ec2-54-202-130-232.us-west-2.compute.amazonaws.com ec2-52-40-225-119.af-south-1.compute.amazonaws.com ec2-54-244-14-137.ap-east-1.compute.amazonaws.com ec2-54-188-91-145.ap-south-1.compute.amazonaws.com ec2-16-221-167-247.ap-northeast-1.compute.amazonaws.com ec2-34-221-167-247.ap-northeast-2.compute.amazonaws.com ec2-34-221-167-247.ap-northeast-3.compute.amazonaws.com ec2-34-221-167-247.ap-southeast-1.compute.amazonaws.com ec2-34-221-167-247.ap-southeast-2.compute.amazonaws.com ec2-34-221-167-247.ap-southeast-3.compute.amazonaws.com ec2-34-221-167-247.ca-central-1.compute.amazonaws.com ec2-34-221-167-247.eu-central-1.compute.amazonaws.com ec2-34-221-167-247.eu-west-1.compute.amazonaws.com ec2-34-221-167-247.eu-west-2.compute.amazonaws.com ec2-34-219-81-114.eu-west-3.compute.amazonaws.com ec2-52-35-119-24.eu-south-1.compute.amazonaws.com ec2-35-160-82-97.eu-north-1.compute.amazonaws.com ec2-34-223-253-69.me-south-1.compute.amazonaws.com ec2-34-216-36-192.sa-east-1.compute.amazonaws.com `; // 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