detecting Firefox private browsing mode

[richardthurman00]

Hi all,

I searched the forums and was not able to come up with an answer to my post. I hope someone can help.

When IE8 launched inPrivateBrowsing, they made code available to detect its use:



if (navigator.userAgent.indexOf("MSIE")>-1) {
if (window != 0) {
if (typeof window.external != "undefined") {
try {
if (window.external.InPrivateFilteringEnabled() == true) {
var isMSIEinPrivate=true;
}
} catch(e){
}
}
}
}


I need to find a similar piece of code that will detect private browsing mode for Firefox 3.5. I thought I had found a solution on developer.mozilla, but I can't make it work.



if (navigator.userAgent.indexOf("Firefox")>-1) {
try {
var pbs = Components.classes["@mozilla.org/privatebrowsing;1"]
.getService(Components.interfaces.nsIPrivateBrowsingService);
var inPrivateBrowsingMode = pbs.privateBrowsingEnabled;

if (inPrivateBrowsingMode) {
var isFFXPrivate=true;
}
} catch(e){
alert("Error Trapped!");
}
}


This always alerts Error Trapped when I view it in Firefox, even in 3.5 with Private Browsing mode turned on. Is there a solution via javascript to detect this browsing mode in Firefox?

Thank you in advance for your help.

-- Richard