Regular Expressions

Cheatsheet

  • /abc/ A sequence of characters

  • /[abc]/ Any character from a set of characters

  • /[^abc]/ Any character not in a set of characters

  • /[0-9]/ Any character in a range of characters

  • /x+/ One or more occurrences of the pattern x

  • /x+?/ One or more occurrences, nongreedy

  • /x*/ Zero or more occurrences

  • /x?/ Zero or one occurrence

  • /x{2,4}/ Two to four occurrences

  • /(abc)/ A group

  • /a|b|c/ Any one of several patterns

  • /\d/ Any digit character

  • /\w/ An alphanumeric character (“word character”)

  • /\s/ Any whitespace character

  • /./ Any character except newlines

  • /\b/ A word boundary

  • /^/ Start of input

  • /$/ End of input

Source: Eloquent JavaScript

Examples

  • /\b(0?[1-9]|1[012])-(0?[1-9]|[12]\d|3[01])-([1-2]\d{3})\b/

    Validates a date in a string, and can be used to extract the month, day, and year with exec().

  • /^\/([^\/]+\/)*/

    Matches the path to a directory of a page (used on this website).

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