I am currently developing a site that will make use of HTML5's localStorage. I've read all about the size limitations for different browsers. However, I haven't seen anything on how to find out the current size of a localStorage instance. This question seems to indicate that JavaScript doesn't have a built in way of showing the size for a given variable. Does localStorage have a memory size property that I haven't seen? Is there an easy way to do this that I'm missing?
My site is meant to allow users to enter information in an 'offline' mode, so being able to give them a warning when the storage is almost full is very important.
IE has a remainingSpace property of the Storage object. The other browsers have no equivilant at this time.
I believe that the default amount of space is 5MB, although I have not tested it personally.