Thanks for the pointer True, read and write actions via dot notation work fine in all browsers supporting localStorage, and advising against it might be a little too strong. Still I can’t find the IDL that describes this, and, what’s more important, using dot notation might leave the impression that localStorage is just an object like any other – but it isn’t.

So just for the sake of clarity and code readability, I’d still go for the “API” methods

There is another method to retrieve a value, but as this not documented (at least I didn’t find anything about it), I do not recommend it:
var value = localStorage.key;

According to Anne van Kesteren, there’s nothing wrong with that technique and it’s okay to use it. No need to advise against it http://krijnhoetmer.nl/irc-logs/whatwg/20100913#l-181