Hey all,

I have an application that I am writing that modifies data on a cached object in the server. The modifications are performed through an ajax call that basically updates properties of that object. When the user is done working, I have a basic 'Save Changes' button that allows them to Save the data and flush the cached object.

In order to protect the user, I want to warn them if the try to navigate away from the page when modifications have been made to the server object if they have not saved. So, I created a web service method called IsInitialized that will return true or false based on whether or not changes have been saved. If they have not been saved, I want to prompt the user and give them a chance to cancel their navigation request.

Here's my problem - although I have the calls working correctly, I can't seem to get the ajax success call to set the variable value on its callback function. Here's the code I have now.

   ////Catches the users to keep them from navigation off the page w/o saved changes...
window.onbeforeunload = CheckSaveStatus;
var IsInitialized;

function CheckSaveStatus() {

    var temp = $.ajax({
    	type: "POST",
    	url: "URL.asmx/CheckIfInstanceIsInitilized",
    	data: "{}",
    	contentType: "application/json; charset=utf-8",
    	dataType: "json",
    	success: function(result) {
    		IsInitialized = result.d;
    	},
    	error: function(xmlHttpRequest, status, err) {
    		alert(xmlHttpRequest.statusText + " " + xmlHttpRequest.status + " : " + xmlHttpRequest.responseText);
    	}

    });

    if (IsInitialized) {
    	return "You currently have unprocessed changes for this Simulation.";
    }
}

I feel that I might be trying to use the Success callback in an inappropriate manner. How do I set a javascript variable on the Success callback so that I can decide whether or not the user should be prompted w/ the unsaved changes message?

As was just pointed out, I am making an asynchronous call, which means the rest of the code gets called before my method returns. Is there a way to use that ajax call, but still catch the window.onunload event? (without making synchronos ajax)