Web storage and Internet Explorer

Web storage is supported on Internet Explorer versions 8, 9, 10, and 11, and according to various websites, Internet Explorer allows each domain to store 10Mb of data.

At least that is the official story.

There are some comments on some websites that web storage doesn`t always work as well as it should on Internet Explorer - my own experience on two different machines with Windows 7 is that web storage works on IE 9, but not fully on IE 10 or 11.

What follows is based on IE 9 on Windows 7.

I haven`t found any way of seeing what is stored in local storage from within Internet Explorer, however there are other ways of seeing it.

The first is to use Windows Explorer to have a look at the folder / folders that IE uses to store the data in.

The path is

 

     Windows(C:)\

        Users\

           <USERNAME>\

              Appdata\

                 LocalLow\

                    Microsoft\

                       Internet Explorer\

                          DOMStore\

In there you should find some folders containing XML files, and a file "index.dat" - all of these can be opened and read with Notepad.

The more technically competent can also look in the registry in

 

     HKey_Current_User\

        Software\

           Microsoft\

              Internet Explorer\

                 LowRegistry\

                    DOMStorage\

and you will find a key for each domain that has stored data using local storage, as well as one called "Total", which shows the total amount of storage space used.

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I haven`t found any way to see where Internet Explore specifies how much storage space is allocated to each domain, or if it limits the total amount of storage space that can be used by all domains.

I can`t find it on the web, and I can`t find it in the registry - it may there somewhere, but as I say, I can`t find it.

Just as with Chrome, there does seem to be a bit of a conspiracy amongst some browser developers to keep web storage under the radar - and good for Firefox and Opera both of which allow it to be a user settable parameter.

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However in its favour, Internet Explorer does allow you to configure IE to delete local storage either manually, or automatically when the browser closes.

It is done through the "General" tab on the "Internet Options" window.

tick the box for "Delete browsing history on exit"
click on the "Delete" button
untick the first box - "Preserve Favourites website data"
tick all the other boxes - unless you really want to keep something- personally, I would remove everything
click on the "Delete" button, and the window closes
click on the "OK" button

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There are another couple of options available to you in the "Internet Options" window.

click on the "Advanced" tab
scroll almost down to the bottom of the list of options
look for the tick box for "Empty Temporary Internet Files folder when browser is closed"
again, personally, I would tick this box
look for the tick box for "Enable DOM Storage"
unticking this box should kill web storage on your browser, but this will break some websites.

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It appears that using the built in delete facility in IE 9 does empty the various folders, but it doesn`t empty the "index.dat" file, which I think gets over-written next time around.

So that does mean that there is still a record of the sites that set data, even if the data itself is no longer there.

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On a 64 bit machine running IE 10 or 11, the "index.dat" file doesn`t exist - instead there is a file called "container.dat", which remains empty - even though a website does put data into one of the various folders.

At this point I am not sure if the use of "container.dat" is to do with the fact it is a 64 bit machine, or whether it is to do with IE 10 or 11 - I don`t have access to enough machines to test all combinations.

I`m also not sure if the fact that the "container.dat" file remains empty is a bug or something Microsoft is doing deliberately - it certainly makes it difficult for other software to find the stored data, which is good news if local storage is being used maliciously for user tracking.

The registry entry shown above is valid for both the 32 bit and the 64 bit versions of IE 10 on 64 bit Windows 7.

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