title: On a browser, sessionStorage in Safari's Private Browsing does not work the same as Chrome's Incognito Mode and Firefox's Private Window?
body: <p>It seems that for <code>sessionStorage</code>, it works differently on Chrome's Incognito Mode vs Safari's Private Browsing and Firefox's Private Window?  I can find something on <a href="http://www.webdirections.org/blog/webstorage-persistent-client-side-data-storage/">http://www.webdirections.org/blog/webstorage-persistent-client-side-data-storage/</a> but it doesn't say that Safari's Private Browsing will throw an exception.</p>
  
  <p>The following is how I opened "Private Browsing":</p>
  
  <ol>
  <li>On Safari on Mac, click "Safari -> Private Browsing" on the menu bar</li>
  <li>On Chrome, use "File -> New Incognito Window"</li>
  <li>On Firefox, use "File -> New Private Window"</li>
  </ol>
  
  <p>and on Safari, <code>sessionStorage</code> does not work, and if I do the following in the console:</p>
  
  <pre><code>&gt; sessionStorage["foo"] = 123.4
  Error: QUOTA_EXCEEDED_ERR: DOM Exception 22
  
  &gt; sessionStorage["foo"] 
  undefined
  </code></pre>
  
  <p>but on Chrome or Firefox, <code>sessionStorage</code> works as usual (as non-private browsing).  Is the above accurate as far as <code>sessionStorage</code> is concerned?</p>