How to manage a redirect request after a jQuery Ajax call

Question

I'm using $.post() to call a servlet using Ajax and then using the resulting HTML fragment to replace a div element in the user's current page. However, if the session times out, the server sends a redirect directive to send the user to the login page. In this case, jQuery is replacing the div element with the contents of the login page, forcing the user's eyes to witness a rare scene indeed.

How can I manage a redirect directive from an Ajax call with jQuery 1.2.6?

Answer

The solution that was eventually implemented was to use a wrapper for the callback function of the Ajax call and in this wrapper check for the existence of a specific element on the returned HTML chunk. If the element was found then the wrapper executed a redirection. If not, the wrapper forwarded the call to the actual callback function.

For example, our wrapper function was something like:

function cbWrapper(data, funct){
    if($("#myForm", data).length > 0)
        top.location.href="login.htm";//redirection
    else
        funct(data);
}

Then, when making the Ajax call we used something like:

$.post("myAjaxHandler", 
       {
        param1: foo,
        param2: bar
       },
       function(data){
           cbWrapper(data, myActualCB);
       }, 
       "html"
);

This worked for us because all Ajax calls always returned HTML inside a DIV element that we use to replace a piece of the page. Also, we only needed to redirect to the login page.