Routing is a key piece of every web application. At its heart, routing involves taking a URL, applying some pattern matching or other app-specific logic to it, and then, usually, displaying web content based on the result. Routing might be implemented in a number of ways: it's sometimes code running on a server that maps a path to files on disk, or logic in a single-page app that waits for changes to the current location and creates a corresponding piece of DOM to display.
URLPattern is a proposed addition to the web platform that builds on the foundation created by these frameworks. Its goal is to standardize a routing pattern syntax, including support for wildcards, named token groups, regular expression groups, and group modifiers. URLPattern instances created with this syntax can perform common routing tasks, like matching against full URLs or a URL pathname, and returning information about the token and group matches.