Filtering functions

Reference documentation for Expressif functions in the text/filtering scope.

Name	Overview
filter-chars	Returns only those characters specified in the parameter, in the order, they were originally entered in the input value.
retain-alpha	Returns the input string with all characters removed except for letters (A-Z, a-z). If the argument is null, it returns null.
retain-alpha-numeric	Returns the input string with all characters removed except for letters (A-Z, a-z) and digits (0-9). If the argument is null, it returns null.
retain-numeric	Returns the input string with all non-numeric characters removed, leaving only digits (0-9).. If the argument is null, it returns null.
retain-numeric-symbol	Returns the input string with all characters removed except for digits (0-9) and the symbols +, -, , and . If the argument is null, it returns null.