456 Part II: Developing an Ajax Library^
They have also used techniques on the unload of the page:window.unload = function () {window.history.forward(1);};The downside with this is that the page has unloaded, so when it forwards the user, it
puts them back to the problem state of the application:If you think that these techniques seem a bit hackish, you aren’t alone. This isn’t the right
approach in most cases, and it turns out that the premature unload problem is such a prevalent
issue that the major browser vendors have adopted a psueudo-standard onbeforeunload
handler to address the concern. We add this small bit of code to our application:window.onbeforeunload = function () {return "";};The user is now prompted with a dialog to warn that they will lose position in the Web
application if they continue.If we desire, a message string can be passed back in the onbeforeunload handler to
customize the message:window.onbeforeunload = function () {return "Are you sure you want to leave
the Photo viewer?";};