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

/
/
gu

Test String

Code Generator

Generated Code

import Foundation // WARNING: You included a flag that Swift doesn't support: u // When this flag is set, it makes the pattern and subject strings to be treated as unicode. // Swift already treats the pattern and subject strings as unicode by default, so including this flag is redundant. let pattern = #"(?<=^|[\n;](?:[\t ]*(?:\w+ )?)?)(?:(?:const\s*|let\s*|var\s*)?(?<imports>(?:[$_\p{ID_Start}][$\u200C\u200D\p{ID_Continue}]*)|(?<=const\s*|let\s*|var\s*)(?:[\w\t\n\r "$'*,./:{}-]+?))\s*=\s*)?(?:await\s+)?(?<expression>import\((?<specifier>[\S\t\n\r]+?)(?:,\s*(?<options>\{\s*assert:.+[\w\t\n\r "':]+\}\s*\}))?\))"# let regex = try! NSRegularExpression(pattern: pattern) let testString = #""" await import(foo) await import('foo') const foo = await import('bar') const foo = await import(bar) const promise = import('./foo'); const { readPackage } = await import('read-pkg') const { readPackageUp, readPackageUpSync } = await import('read-pkg'); const { addFive, addFour, addThree, addTwo, squareFive, squareFour, squareThree, squareTwo } = await import('./lib') await import('buzz').then(() => console.log(res)).catch(() => ({})) var g;const{foo}=await import('bar');const{ foo }=await import('bar') import('buzz').then(() => console.log(res)).catch(() => ({})) import('buzz').then(() => console.log(res)).catch(() => ({})) import('buzz').catch(() => ({})) const foo = "./utils.mjs"; await import(foo) const { default: barData } = await import('./bar.json'); const { default: barData } = await import('./bar.json', { assert: { type: 'json' } }); (async () => { if (somethingIsTrue) { // import module for side effects await import("/modules/my-module.js"); } })(); await import('__tests__/report.json', { assert: { type: 'json' } }) await import('__tests__/report.json', { assert: { type: 'json' } }) (async () => { if (somethingIsTrue) { const { default: myDefault, foo, bar, } = await import("/modules/my-module.js"); } })(); const main = document.querySelector("main"); for (const link of document.querySelectorAll("nav > a")) { link.addEventListener("click", (e) => { e.preventDefault(); import("/modules/my-module.js") .then((module) => { module.loadPageInto(main); }) .then((module) => { module.loadPageInto(main); }) .then((module) => { module.loadPageInto(main); }) .catch((err) => { main.textContent = err.message; }); }); } let myModule; if (typeof window === "undefined") { myModule = await import("module-used-on-server"); } else { myModule = await import("module-used-in-browser"); } Promise.all( Array.from({ length: 10 }).map((_, index) => import(`/modules/module-${index}.js`) ) ).then((modules) => modules.forEach((module) => module.load())); Array.from({ length: 10 }).map((_, index) => { return import(`/modules/module-${index}.js`) }) 'await import("foo")' "await import('foo')" // await import('foo') /** * @example * const { readPackageUp } = await import('read-pkg') */ """# let stringRange = NSRange(location: 0, length: testString.utf16.count) let matches = regex.matches(in: testString, range: stringRange) var result: [[String]] = [] for match in matches { var groups: [String] = [] for rangeIndex in 1 ..< match.numberOfRanges { let nsRange = match.range(at: rangeIndex) guard !NSEqualRanges(nsRange, NSMakeRange(NSNotFound, 0)) else { continue } let string = (testString as NSString).substring(with: nsRange) groups.append(string) } if !groups.isEmpty { result.append(groups) } } print(result)

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 Swift 5.2, please visit: https://developer.apple.com/documentation/foundation/nsregularexpression