[Bug]: useParams hook regularly makes new params empty object

[JasonKleban]

What version of React Router are you using?

6

Steps to Reproduce

react-router/packages/react-router/lib/hooks.tsx

Line 236 in 38359a9

return routeMatch ? (routeMatch.params as any) : {};

Expected Behavior

I think this should be some constant emptyObj reuse instead of made anew because it causes rerenders.

I'm also seeing truthy a routeMatch give an identical object over and over but I was under the impression that this was fixed in v6 with #7059 and #8431.

Actual Behavior

returns a new {} every time.

or when routeMatch is truthy, unnecessary rerenders with something like { "*": "" } as the return value.

[timdorr]

You shouldn't be using the entire result of useParams in your dependencies for React hooks. If you navigate and don't change the params values, you'll have the same problem as the object will still be recreated. Instead, you should check specific params that you care about. That will ensure you don't re-render when it's not needed, regardless of what the state of params is.