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]
  • Character class intersection
    [\w&&[^\d]]
  • 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

Generated Code

import re regex = re.compile(r"^(?:[\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?)?)?(?:\;)?$", flags=re.IGNORECASE | re.MULTILINE) test_str = ("/**\n" " * @function\n" " * @description simple method that tries to retrieve a config value from the format\n" " * if it exists, else it will return the second argument as the default value.\n" " * @param {string} prop - the prop name to retrieve\n" " * @param {any} defaultValue - the value to use if we can't extract from the format\n" " * @returns {any} - the default value or extracted format value\n" " */\n\n\n" "const a = {\n" " apples() {\n\n" " },\n" " apples2 : function() {\n" " },\n" " apples3 : () => {\n" " }\n" "}\n\n" "function(){}\n\n" "function() {}\n\n" "function() { }\n" "function () { }\n" "function (arg, asdf) { }\n" "function (arg, asdf):Typings { }\n" "function (arg, asdf):something<Else> { }\n\n" "function () { }\n" "const x = function () { }\n" "const { x } = function () { }\n\n" "const { x: asdf } = function () { }\n\n" "const filterFn = () => {}\n\n" "// won't grab\n" "const filterFn = apples.filter(() => {});\n" "// won't grab\n" "const filterFn = apples.filter(function(){});\n\n\n\n" "class Bla {\n" " constructor() {\n" " }\n" " someMethod1() {\n" " }\n" " someMethod2() => {\n" " }\n" " get someMethod3() {\n" " }\n" "}\n\n\n" "/**\n" " * @function\n" " * @description simple method that tries to retrieve a config value from the format\n" " * if it exists, else it will return the second argument as the default value.\n" " * @param {string} prop - the prop name to retrieve\n" " * @param {any} defaultValue - the value to use if we can't extract from the format\n" " * @returns {any} - the default value or extracted format value\n" " */\n" "HoverBoard.prototype.getFormatValueIfExists = function (prop, defaultValue) {\n" " try {\n" " return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue;\n" " } catch (e) {\n" " return defaultValue;\n" " }\n" "};\n\n" "/**\n" " * @function\n" " * @description simple method that tries to retrieve a config value from the format\n" " * if it exists, else it will return the second argument as the default value.\n" " * @param {string} prop - the prop name to retrieve\n" " * @param {any} defaultValue - the value to use if we can't extract from the format\n" " * @returns {any} - the default value or extracted format value\n" " */\n" "const getFormatValueIfExists = function (prop, defaultValue) {\n" " try {\n" " return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue;\n" " } catch (e) {\n" " return defaultValue;\n" " }\n" "};\n\n" "/**\n" " * @function\n" " * @description simple method that tries to retrieve a config value from the format\n" " * if it exists, else it will return the second argument as the default value.\n" " * @param {string} prop - the prop name to retrieve\n" " * @param {any} defaultValue - the value to use if we can't extract from the format\n" " * @returns {any} - the default value or extracted format value\n" " */\n" " var getFormatValueIfExists = (prop, defaultValue) => {\n" " try {\n" " return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue;\n" " } catch (e) {\n" " return defaultValue;\n" " }\n" "};\n\n" "/**\n" " * @function\n" " * @description simple method that tries to retrieve a config value from the format\n" " * if it exists, else it will return the second argument as the default value.\n" " * @param {string} prop - the prop name to retrieve\n" " * @param {any} defaultValue - the value to use if we can't extract from the format\n" " * @returns {any} - the default value or extracted format value\n" " */\n" "window.x = (prop, defaultValue) => {\n" " try {\n" " return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue;\n" " } catch (e) {\n" " return defaultValue;\n" " }\n" "};\n\n" "/**\n" " * @function\n" " * @description simple method that tries to retrieve a config value from the format\n" " * if it exists, else it will return the second argument as the default value.\n" " * @param {string} prop - the prop name to retrieve\n" " * @param {any} defaultValue - the value to use if we can't extract from the format\n" " * @returns {any} - the default value or extracted format value\n" " */\n" "something.else.x = (prop, defaultValue) => {\n" " try {\n" " return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue;\n" " } catch (e) {\n" " return defaultValue;\n" " }\n" "};\n\n\n" "/**\n" " * @function\n" " * @description simple method that tries to retrieve a config value from the format\n" " * if it exists, else it will return the second argument as the default value.\n" " * @param {string} prop - the prop name to retrieve\n" " * @param {any} defaultValue - the value to use if we can't extract from the format\n" " * @returns {any} - the default value or extracted format value\n" " */\n" "var x = null;\n" "x = (prop, defaultValue) => {\n" " try {\n" " return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue;\n" " } catch (e) {\n" " return defaultValue;\n" " }\n" "};\n\n\n" "/**\n" " * @function\n" " * @description simple method that tries to retrieve a config value from the format\n" " * if it exists, else it will return the second argument as the default value.\n" " * @param {string} prop - the prop name to retrieve\n" " * @param {any} defaultValue - the value to use if we can't extract from the format\n" " * @returns {any} - the default value or extracted format value\n" " */\n" "function getFormatValueIfExists(prop, defaultValue) {\n" " try {\n" " return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue;\n" " } catch (e) {\n" " return defaultValue;\n" " }\n" "};\n\n" "/**\n" " * @function\n" " * @description simple method that tries to retrieve a config value from the format\n" " * if it exists, else it will return the second argument as the default value.\n" " * @param {string} prop - the prop name to retrieve\n" " * @param {any} defaultValue - the value to use if we can't extract from the format\n" " * @returns {any} - the default value or extracted format value\n" " */\n" "function (prop, defaultValue) {\n" " try {\n" " return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue;\n" " } catch (e) {\n" " return defaultValue;\n" " }\n" "};\n\n" "/**\n" " * @function\n" " * @description simple method that tries to retrieve a config value from the format\n" " * if it exists, else it will return the second argument as the default value.\n" " * @param {string} prop - the prop name to retrieve\n" " * @param {any} defaultValue - the value to use if we can't extract from the format\n" " * @returns {any} - the default value or extracted format value\n" " */\n" "(prop, defaultValue) => {\n" " try {\n" " return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue;\n" " } catch (e) {\n" " return defaultValue;\n" " }\n" "};\n\n" "/**\n" " * @function\n" " * @description simple method that tries to retrieve a config value from the format\n" " * if it exists, else it will return the second argument as the default value.\n" " * @param {string} prop - the prop name to retrieve\n" " * @param {any} defaultValue - the value to use if we can't extract from the format\n" " * @returns {any} - the default value or extracted format value\n" " */\n" "((prop, defaultValue) => {\n" " try {\n" " return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue;\n" " } catch (e) {\n" " return defaultValue;\n" " }\n" "}());\n\n\n\n\n" "/**\n" " * @function\n" " * @description simple method that tries to retrieve a config value from the format\n" " * if it exists, else it will return the second argument as the default value.\n" " * @param {string} prop - the prop name to retrieve\n" " * @param {any} defaultValue - the value to use if we can't extract from the format\n" " * @returns {any} - the default value or extracted format value\n" " */\n" "((prop, defaultValue) => {\n" " try {\n" " return typeof this.config.formats[this.name][prop] !== 'undefined' ? this.config.formats[self.name][prop] : defaultValue;\n" " } catch (e) {\n" " return defaultValue;\n" " }\n" "} (window) );\n\n") matches = regex.finditer(test_str) for match_num, match in enumerate(matches, start=1): print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}") for group_num, group in enumerate(match.groups(), start=1): print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")

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 Python, please visit: https://docs.python.org/3/library/re.html