Question

Since localStorage (currently) only supports strings as values, and in order to do that the objects need to be stringified (stored as JSON-string) before they can be stored, is there a defined limitation regarding the length of the values.

Does anyone know if there is a definition which applies to all browsers?

Answer 1

Quoting from the Wikipedia article on Web Storage:

Web storage can be viewed simplistically as an improvement on cookies, providing much greater storage capacity (10 MB per origin in Google Chrome(https://plus.google.com/u/0/+FrancoisBeaufort/posts/S5Q9HqDB8bh), Mozilla Firefox, and Opera; 10 MB per storage area in Internet Explorer) and better programmatic interfaces.

And also quoting from a John Resig article [posted January 2007]:

Storage Space

It is implied that, with DOM Storage,
you have considerably more storage
space than the typical user agent
limitations imposed upon Cookies.
However, the amount that is provided
is not defined in the specification,
nor is it meaningfully broadcast by
the user agent.

If you look at the Mozilla source code
we can see that 5120KB is the default
storage size for an entire domain.
This gives you considerably more space
to work with than a typical 2KB
cookie.

However, the size of this storage area
can be customized by the user (so a
5MB storage area is not guaranteed,
nor is it implied) and the user agent
(Opera, for example, may only provide
3MB – but only time will tell.)