I naively assumed from the headline that the author would complain about users blocking cookies. I was very pleasantly surprised to see a post written by someone who appreciates that some users will want to do this and is actively working to support delivering them a useful content experience!
I have written a web app that does this so you can share links which have the same state. You can't have that long of URLs actually - especially for some browsers.
Having to base64 encode most/all of it so you can safely use any kind of data makes it even worse.
My use case was very basic and I quickly hit limits that made it so I couldn't "persist" all of the data I wanted.
Er, you'd store the data in your DB of course and only a comparatively small, encrypted index to it in the URL. You wouldn't trust the client to "persist" the data anyhow.
I think the poster is referring to things like "offline Google Docs editing that can survive a browser shutdown or crash" which would be... difficult... to cram into a URL ;)
> what the heck is so important that folks need to cookie that can't be just tied to the session token in the backend?
Storing information on the client makes your site a lot more transparent about what it's keeping. If I have various user preferences in local storage you can tell that's what I'm doing and why, but if I just cookie you with an opaque token you have no idea what I'm tracking with that on the server.
While this can help, it needs to be done alongside network traffic analysis. If you type your name/phone number/address into (for example) a resume template, and you see that information stored in the local client, you don't know whether that information is also stored on the server.
Ignore the "length" (implementation detail) and you can see it's storing whether I've turned on dark mode and some id that's likely per-user. If I switch the page to dark mode I see instead:
You could also just use the Storage tab in the devtools of your browser of choice, Chrome and Firefox at least both provide a GUI for looking at storage. Not sure what all Chrome's shows, but Firefox's shows Cache Storage, Cookies, IndexedDB, LocalStorage, and SessionStorage.
As someone working on a ticketing purchase flow, this is critical... can't exactly just turn people away! I was also surprised about localstorage throwing exceptions.
Given that many cookie banners still (IMHO illegally, to be verified by courts) give the choices "accept tracking or fuck off" I guess you could. But it behoves you that you would assume it's a stupid idea. :)
