I've had this thought experiment before, but where I get stuck is - what happens when you want to share state between the pages? URL params, storing to indexedD

I've had this thought experiment before, but where I get stuck is - what happens when you want to share state between the pages? URL params, storing to indexedDB, sticking them in global variables - all viable solutions but all with their own issues. I'd be very interested to hear how you solve this, or if it's less of an issue than people might think.