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Spread operator "..."

Regex expressions are a tool used to match specific string sequence in long string

Methods

1
/regex/.test('string'); // Return true or false

1
'string'.match(/regex/); // Return a list of matching strings

1
'string'.replace(/regex/, 'replaceString'); // Return a list of matching strings
Important

You can also access capture groups in the replacement string with dollar signs ($).

1
    "Code Camp".replace(/(\w+)\s(\w+)/, '$2 $1')

Operators

Method Description
/platypus/ Match the exact string
/yes|no/ Match 'yes' or 'no' strings
/freecodecamp/i Case insensitive
/repeat/g Several matching patterns
/.hu/ Ends with hu
/h+/ One or more h
/go*/ Zero or more o after a g
/[aiu]/ a, i or u
/[a-e]/ Between a and e
/[0-9]/ Between 0 and 9
/[^aeiou]/ No vowels
/<.*?>/ Lazy match instead of default greedy
/^Cal/ Sequence starts with Cal
/Cal$/ Sequence ends with Cal
/\w/ = /[A-Za-z0-9_]/ Any letter/number/underscore
/\W/ = /[^A-Za-z0-9_]/ No letter/number/underscore
/\d/ = /[0-9]/ Any digit
/\D/ = /[^0-9]/ No digit
/\s/ = /[ \r\t\f\n\v]/ Any Whitespace (CR, tab, NL, space)
/\S/ = /[^ \r\t\f\n\v]/ No Whitespace (CR, tab, NL, space)
/a{3,5}/ 3 to 5 a
/a{3,}/ 3 or more a
/a{3}/ Exactly 3 a
/colou?r/ Check for 0 or 1 u in color
(?=\w)(?!u) Any letter but u
/P(engu|umpk)in/ Penguin or Pumpkin
/(\w+)(\s)\1\2\1/ Any word occuring 3 times with spaces