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

/
/
gim

Test String

Code Generator

Generated Code

const regex = /^(?:[\s]+)?(?:const|let|var|)?(?:[a-z0-9.]+(?:\.prototype)?)?(?:\s)?(?:[a-z0-9-_{}:\s]+\s?=)?\s?(?:[a-z0-9]+\s+\:\s+)?(?:function\s?)?(?:[a-z0-9_-]+)?\s?\(.*\)\s?(?:.+)?([=>]:)?\{(?:(?:[^}{]+|\{(?:[^}{]+|\{[^}{]*\})*\})*\}(?:\s?\(.*\)\s?\)\s?)?)?(?:\;)?$/gim; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(?:[\\s]+)?(?:const|let|var|)?(?:[a-z0-9.]+(?:\\.prototype)?)?(?:\\s)?(?:[a-z0-9-_{}:\\s]+\\s?=)?\\s?(?:[a-z0-9]+\\s+\\:\\s+)?(?:function\\s?)?(?:[a-z0-9_-]+)?\\s?\\(.*\\)\\s?(?:.+)?([=>]:)?\\{(?:(?:[^}{]+|\\{(?:[^}{]+|\\{[^}{]*\\})*\\})*\\}(?:\\s?\\(.*\\)\\s?\\)\\s?)?)?(?:\\;)?$', 'gim') const str = `/** * @function * @description simple method that tries to retrieve a config value from the format * if it exists, else it will return the second argument as the default value. * @param {string} prop - the prop name to retrieve * @param {any} defaultValue - the value to use if we can't extract from the format * @returns {any} - the default value or extracted format value */ const a = { apples() { }, apples2 : function() { }, apples3 : () => { } } function(){} function() {} function() { } function () { } function (arg, asdf) { } function (arg, asdf):Typings { } function (arg, asdf):something<Else> { } function () { } const x = function () { } const { x } = function () { } const { x: asdf } = function () { } const filterFn = () => {} // won't grab const filterFn = apples.filter(() => {}); // won't grab const filterFn = apples.filter(function(){}); class Bla { constructor() { } someMethod1() { } someMethod2() => { } get someMethod3() { } } /** * @function * @description simple method that tries to retrieve a config value from the format * if it exists, else it will return the second argument as the default value. * @param {string} prop - the prop name to retrieve * @param {any} defaultValue - the value to use if we can't extract from the format * @returns {any} - the default value or extracted format value */ HoverBoard.prototype.getFormatValueIfExists = function (prop, defaultValue) { try { return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue; } catch (e) { return defaultValue; } }; /** * @function * @description simple method that tries to retrieve a config value from the format * if it exists, else it will return the second argument as the default value. * @param {string} prop - the prop name to retrieve * @param {any} defaultValue - the value to use if we can't extract from the format * @returns {any} - the default value or extracted format value */ const getFormatValueIfExists = function (prop, defaultValue) { try { return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue; } catch (e) { return defaultValue; } }; /** * @function * @description simple method that tries to retrieve a config value from the format * if it exists, else it will return the second argument as the default value. * @param {string} prop - the prop name to retrieve * @param {any} defaultValue - the value to use if we can't extract from the format * @returns {any} - the default value or extracted format value */ var getFormatValueIfExists = (prop, defaultValue) => { try { return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue; } catch (e) { return defaultValue; } }; /** * @function * @description simple method that tries to retrieve a config value from the format * if it exists, else it will return the second argument as the default value. * @param {string} prop - the prop name to retrieve * @param {any} defaultValue - the value to use if we can't extract from the format * @returns {any} - the default value or extracted format value */ window.x = (prop, defaultValue) => { try { return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue; } catch (e) { return defaultValue; } }; /** * @function * @description simple method that tries to retrieve a config value from the format * if it exists, else it will return the second argument as the default value. * @param {string} prop - the prop name to retrieve * @param {any} defaultValue - the value to use if we can't extract from the format * @returns {any} - the default value or extracted format value */ something.else.x = (prop, defaultValue) => { try { return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue; } catch (e) { return defaultValue; } }; /** * @function * @description simple method that tries to retrieve a config value from the format * if it exists, else it will return the second argument as the default value. * @param {string} prop - the prop name to retrieve * @param {any} defaultValue - the value to use if we can't extract from the format * @returns {any} - the default value or extracted format value */ var x = null; x = (prop, defaultValue) => { try { return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue; } catch (e) { return defaultValue; } }; /** * @function * @description simple method that tries to retrieve a config value from the format * if it exists, else it will return the second argument as the default value. * @param {string} prop - the prop name to retrieve * @param {any} defaultValue - the value to use if we can't extract from the format * @returns {any} - the default value or extracted format value */ function getFormatValueIfExists(prop, defaultValue) { try { return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue; } catch (e) { return defaultValue; } }; /** * @function * @description simple method that tries to retrieve a config value from the format * if it exists, else it will return the second argument as the default value. * @param {string} prop - the prop name to retrieve * @param {any} defaultValue - the value to use if we can't extract from the format * @returns {any} - the default value or extracted format value */ function (prop, defaultValue) { try { return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue; } catch (e) { return defaultValue; } }; /** * @function * @description simple method that tries to retrieve a config value from the format * if it exists, else it will return the second argument as the default value. * @param {string} prop - the prop name to retrieve * @param {any} defaultValue - the value to use if we can't extract from the format * @returns {any} - the default value or extracted format value */ (prop, defaultValue) => { try { return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue; } catch (e) { return defaultValue; } }; /** * @function * @description simple method that tries to retrieve a config value from the format * if it exists, else it will return the second argument as the default value. * @param {string} prop - the prop name to retrieve * @param {any} defaultValue - the value to use if we can't extract from the format * @returns {any} - the default value or extracted format value */ ((prop, defaultValue) => { try { return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue; } catch (e) { return defaultValue; } }()); /** * @function * @description simple method that tries to retrieve a config value from the format * if it exists, else it will return the second argument as the default value. * @param {string} prop - the prop name to retrieve * @param {any} defaultValue - the value to use if we can't extract from the format * @returns {any} - the default value or extracted format value */ ((prop, defaultValue) => { try { return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue; } catch (e) { return defaultValue; } } (window) ); `; // 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