patmat | An attempt at pattern matching in JavaScript | Regex library

patmat is a JavaScript library typically used in Utilities, Regex applications. patmat has no bugs, it has no vulnerabilities, it has a Permissive License and it has low support. You can install using 'npm i @ygunayer/patmat' or download it from GitHub, npm.

Put simply, pattern matching is the act of checking whether an expression matches a certain pattern. Languages such as Rust, Scala, and Erlang implement this concepts as a core language feature, and while there is a proposal to add it at some point, there's currently no such support in JavaScript. As the name implies, pattern matching attempts to match expressions to patterns. These patterns may range from scalar values (think switch..case statements) to dynamic expressions, and from type matching to destructed array or object patterns, and to even regular expressions. When a match is found, the function or expression block the pattern points to is invoked either with the input variable, or the output of the match expression (e.g. the result of the regex match), and the result of that expression is then returned as the result of the entire pattern matching expression. Case handles in pattern matching may also contain catch-all expressions that can either match entire expressions (like the default keyword in switch..case statements), or a part of the expression (like filler values). In Erlang, Rust and Scala, the special keyword _ can be used to achieve this purpose (though in Erlang's case it's not technically a keyword, but an arbitrary match variable). Case handles can also contain an additional inner expression called guard expressions that further increase the accuracy of the match. Let's see a few examples to demonstrate each quirk.