AJAX Magazine: AJAX Timeouts with Prototype

Jason have an interesting post on AJAX Timeouts with Prototype, excellent to solve the network issues and keep control on it. A feature that Gmail handle it very nicely by displaying an alert message when there is network problems. The code is commented and its very well self explanatory

callInProgress: function(xmlhttp) {
switch (xmlhttp.readyState) {
case 1: case 2: case 3:
return true;
break;
// Case 4 and 0
default:
return false;
break;
}
}
function showFailureMessage() {
alert('uh oh, it looks like the network is down. Try again shortly');
}
// Register global responders that will occur on all <acronym title="Asynchronous Javascript And XML">AJAX</acronym> requests
Ajax.Responders.register({
onCreate: function(request) {
request['timeoutId'] = window.setTimeout(
function() {
// If we have hit the timeout and the <acronym title="Asynchronous Javascript And XML">AJAX</acronym> request is active, abort it and let the user know
if (callInProgress(request.transport)) {
request.transport.abort();
showFailureMessage();
// Run the onFailure method if we set one up when creating the <acronym title="Asynchronous Javascript And XML">AJAX</acronym> object
if (request.options['onFailure']) {
request.options['onFailure'](request.transport, request.json);
}
}
},
5000 // Five seconds
);
},
onComplete: function(request) {
// Clear the timeout, the request completed ok
window.clearTimeout(request['timeoutId']);
}
});

I’ve been implementing some AJAX goodness in Mayday and other FastFrame apps lately. In my reading of the various pitfalls of AJAX one that popped up repeatedly was how to handle gracefully a network outage or the webserver going down. For example, Gmail’s chat handles it nicely. When I turn off my airport connection Gmail chat lets me know that it can’t contact the server and maybe my connection is down. Much better than an endlessly spinning hour glass, or worse, not letting the user know their action was never completed.

AJAX Timeouts with Prototype

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