only if you are storing personal information. Email, Name, unique ID.

Something as simple as "blue" doesn't qualify.

Correct. But you can also use cookies for that, without violating GDPR or the ePrivacy directive.

Then you have the problem of some users blocking cookies at the browser level. LocalStorage is perfect application for this use case.

	▲	account42 2 days ago \| parent [-]
		Or maybe you could respect those user's preferences of not having shit stored for your website.