Can you talk more about this… I was under the impression that was the EXPLICIT reason [1] why it was added in the first place or did I misread your comment?

It’s also something the Lit team uses like here: https://www.npmjs.com/package/@lit-labs/router

I think maybe we are just debating the data structure the hold the patterns? Like it should be a trie rather than say a Set or Map.

[1] https://developer.chrome.com/docs/web-platform/urlpattern

It would take a very large number of routes before linear search would become a noticeable performance problem.

At that point, you’d probably be splitting the router itself into multiple client bundles, with something at the root to quickly match the URL with a bundle of routes (maybe a hash table on the first URL segment, or even a trie).

This URLPattern library and linear search would still be a reasonable choice for implementing each individual route bundle. And in practice, just do it the naive way until it actually becomes a problem.

I just tried to match a URL against about a hundred patterns of various types (thanks to Claude code), expecting it to be a non-issue.

A hundred regex tests, for example, is generally very fast. A quick Python script made them run in 0.85ms. A hundred Flask router tests is 2.64ms.

So I had no reason to think this API would be slow. Surely matching a URL is a subset of generalized regexes and can only be fast? And given that routing is not an activity you do a lot, why would it matter anyway?

But the performances were atrocious: it took 8 seconds to resolve the worst-case scenario on Firefox, and it locked the entire browser UI.

Ok, note to self, stay away from the URL Pattern API.

Also

The class isn’t called URL, it’s called URLPattern. Because it represents a pattern that URLs can be matched against.