Conditional Express Middleware Skipping

express-unless is a utility library for Express.js that enables conditional execution of middleware functions. It allows developers to attach an `unless` method directly to any Express middleware, providing granular control over when that middleware should be skipped. The library currently ships as version 2.1.3 and has seen stable releases, with the latest update in April 2021. It differentiates itself by offering a fluent API for defining skip conditions based on HTTP methods, request paths (including regular expressions and path/method pairs), file extensions, or a fully custom predicate function. This approach simplifies complex conditional routing logic often found in Express applications, providing a cleaner way to apply authentication, logging, or other cross-cutting concerns selectively.