Comment by c-smile

NSUserDefaults is a key-value storage. Same as localStorage in browsers/js.

On other side persistence in QuickJS is more than that. Essentially it is a NoSQL DB integrated into the language and its runtime. For example you can write

   let uname = root.users[2].firstName; 

to access the data using pure language constructs. While with NSUserDefaults you will need to call DB's facade methods like objectForKey("some") and so on.

And also, in QuickJS, Storage is not reading whole DB in memory but fetches/unloads data on demand transparently for the user. You can think about content of DB as about genuine language data structure with root at storage.root