Substitute (.sub())

type returns
Method string

Arguments

name type description
value regex \ string The regex to perform replacements on
replacement string \ (...matches) -> string Replacement for each matches location

Explanation

Matches all occurences of value, with replacement.

value

  • If value is a string. It is matched as appears in the string gloablly, it is not converted to a regular expression.
  • A regular expression's capture groups are passed to the replacement if applicable.

String replacements

If the replacement is a string, the following charcater sequences have special behavior:

name explanation example
$\$ Inserts a literal $ "$\$59.99"
$& Refers to the entire matches string "( $& )"
$n Where n is a number, refers to the nth capture group $2, $1
$` Refers to the match the precedes the given match encountered: $`
$' Refers to the match that follows the given match upcoming: $'

Function replacements

If the replacement is a function, the capture groups are passed in the format ( c1, c2, ..., cn ). The function should return string, otherwise an error will be thrown

Examples

"1 + 1 = 2".sub(/\d+ ([+*/-]) \d/g, "$1") == "+ = 2"
"1 + 1 - 2".sub(/(\d+ )?([+-]) \d+/g, "$'") == " - 2 "
"Hi".sub("i", "ello") == "Hello"

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