WebStorage

Some operations can only really fail because access to web storage has been blocked. This can happen because the user has requested to block all cookies, for example, which also affects local storage.

When reading from web storage, one of two things can go wrong: Either the thing you're asking for does not exist, or you don't have access to the storage (see AccessError).

When writing to web storage, one of two things can go wrong: Either you've run out of disk space (typically, each website origin gets around 5Mb of data), or you don't have access to the storage (see AccessError).