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Question

How do I detect if a user has got to a page using the back button?

Answer 1

A:

As mentioned above, I had found a solution and am posting it here for reference and feedback.

The first stage of the solution is to add the following to the page:

<!-- at the top of the content page -->
<IFRAME id="page_is_fresh" src="fresh.html" style="display:none;"></IFRAME>
<SCRIPT style="text/javascript">
  function reload_stale_page() { location.reload(); }
</SCRIPT>

The contents of fresh.html are not important, so the following should suffice:

<!-- fresh.html -->
<HTML><BODY></BODY></HTML>

When client side code updates the page, it needs to flag the modification as follows:

function trigger_reload_if_user_clicks_back_button()
{
  // "dis-arm" the reload stale page function so it doesn't fire  
  // until the page is reloaded from the browser's cache
  window.reload_stale_page = function(){};

  // change the IFRAME to point to a page that will reload the 
  // page when it loads
  document.getElementById("page_is_fresh").src = "stale.html";
}

stale.html does all the work: When it is loaded it will call the reload_stale_page function which will refresh the page if necessary. The first time it is loaded (i.e. after the modification is made, the reload_stale_page function won't do anything.)

<!-- stale.html -->
<HTML><BODY>
<SCRIPT type="text/javascript">window.parent.reload_stale_page();</SCRIPT>
</BODY></HTML>

From my (minimal) testing at this stage, this seems to work as desired. Have I overlooked anything?

Tom 2009-05-06 11:07:04

Is this browser dependent?

Allain Lalonde 2009-05-06 11:12:40

Not that I know of, but I haven't tested it fully. getElementById isn't supported in some older browsers, but that's easy to swap out for jquery or something if required.

Tom 2009-05-06 12:19:09

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How do I detect if a user has got to a page using the back button?

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