#Firefox refresh page no cache update
F5(Refresh) causes the browser to build a conditional update request if the content originally had a Last-Modified response header.With other embedded resources such as CSS or images, the browser automatically sends the following types of requests depending on whether F5 (Refresh) or Ctrl+F5 (Forced Refresh) is used: This makes the Ajax call behave as if it were a request for an embedded resource.Īs you develop a page like this, it is tempting to refresh the page in an attempt to update the embedded Ajax content. Instead of being triggered by a user event such as a button click, it is directly called from the Javascript that runs when the page is loaded. Sometimes Ajax is used at load time to populate sections of a page (e.g. Fact #2: IE Doesn’t Refresh Ajax Based Content Before Its Expiration Date The 200 response from the server indicates that a fresh copy of the content was downloaded. The final click at 1:06.531 does result in an Ajax request that requires a network round-trip, because the cached data is now more than one minute old. the value in the Sent and Received columns is zero bytes) : In this HttpWatch screenshot you can see that repeated clicks of the update button cause Ajax requests that read directly from the browser cache and result in no network activity (i.e. If you click on the ‘Ajax Update’ button at regular intervals, the time only changes approximately once a minute because the Expires header is set to one minute in the future. In HttpWatch, you can see that we’ve set all three of these headers in the Ajax response: We’ve setup a Ajax caching demo that shows these headers in action.
You should always use the POST method if your Ajax request has side effects, e.g. Of course, this doesn’t apply if you use the POST method in your Ajax requests, because POST requests are never cached.
#Firefox refresh page no cache code
The server would respond with a 304 status code if the data doesn’t require an update. Last-Modified: It’s a good idea to set this so that the browser can use an If-Modified-Since header in a conditional GET request to check its locally cached content.The Expires header allows the browser to reuse the cached content for a period of time and avoid any unnecessary round-trips to the server. For a photograph, you might set a far futures Expires header because you don’t ever expect it to change. For example, if it is a stock price you might set an Expires value 10 seconds in the future. Expires: This should be set to an appropriate time in the future depending on how often the content changes.The following response headers are used to make your Ajax cacheable: The only real difference is that you may need to setup response headers in a different way to static files.
If you know about HTTP caching already, you can apply that knowledge to Ajax caching. It simply obeys the normal HTTP caching rules based on the response headers returned from the server. At this level, the browser doesn’t know or care about Ajax requests. The HTTP and Cache sub-systems of modern browsers are at a much lower level than Ajax’s XMLHttpRequest object. Fact #1 : Ajax Caching Is The Same As HTTP Caching
The rest of this blog post covers two important facts that will help you understand and effectively apply caching to Ajax requests. Make sure your Ajax requests follow the performance guidelines, especially having a far future Expires header. Rule 14 of High Performance Web Sites states: However, due to their dynamic nature people often overlook the benefit of caching them. Augin Caching, Firefox, HTTP, HttpWatch, Internet ExplorerĪjax calls are just like any other HTTP request that might be used to build a web page.
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