As is well known, in XHR (aka AJAX) web applications no history for your app is build and clicking the refresh button often moves the user out of his/her current activity. I stumbled upon location.hash (e.g. http://anywhere/index.html#somehashvalue) to circumvent the refresh problem (use location.hash to inform your app of it's current state and use a page load handler to reset that state). It's really nice and simple.
This brought me to thinking about using location.hash to track the history of my app. I don't want to use existing libraries, because they use iframes etc. So here's my nickel and dime: when the application page loads I start this:
setInterval(
function(){
if (location.hash !== appCache.currentHash) {
appCache.currentHash = location.hash;
appCache.history.push(location.hash);
/* ... [load state using the hash value] ... */
return true;
}
return false;
}, 250
);
(appCache is a predefined object containing application variables) The idea is to trigger every action in the application from the hash value. In decent browsers a hash value change adds an entry to the history, in IE (<= 7) it doesn't. In all browsers, navigating back or forward to a page with another hash value doesn't trigger a page refresh. That's where the intervalled function takes over. With the function everytime the hash value change is detected (programmatically, or by clicking back or forward) the app can take appropriate action. The application can keep track of it's own history and I should be able to present history buttons in the application (especially for IE users).
As far as I can tell this works cross browser and there's no cost in terms of memory or processor resources. So my question is: would this be a viable solution to manage the history in XHR-apps? What are the pros and cons?
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