OptionalkeyDefines middle part of the regular expression to lookup key values,
the default is [\\p{Letter}\\p{Mark}\\d_.$-]+.
OptionalkeyDefines regex flags, like g and u or i.
The default is gu
OptionalkeyDefines postfix of the regular expression to lookup key values, the default is \\}.
OptionalkeyDefines prefix of the regular expression to lookup key values, the default is \\$\\{.
Optionalvaluecustom function to lookup values for keys from the second parameter provided to the created replacer function.
OptionalvalueDefines the value used if the key lookup provides no value, by default this property is undefined, which means that the input key expression is kept.
Replacement Options