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Soon after I first implemented AHAH-based form refreshing in my Facebook-style Statuses module for the Drupal content management system, I realized that the process created something of a workflow problem. Users would go and post a message like normal, and then the form -- and the links on it -- would refresh via AHAH. Essentially, when a user clicked the submit button on the form, some JavaScript would silently open another page (the "callback" page) in the background. That page would generate a new copy of the form, which would then be copied and pasted over the form that had just been submitted.

The problem was, that new copy of the form was generated on the callback page, and it had no way of knowing from what page it had been called. In other words, if the script generating the form wanted to know what the current page was, instead of getting the URL of the page on which the form originally appeared, it would get the URL of the callback page. This became a problem when dealing with links, because links often include a "destination" parameter so that when a user takes an action after clicking the link they will be returned to the appropriate place. For example, an "edit" link for a message would typically have a "destination" parameter in the URL so that when a user saved the edits, the browser would automatically send the user back to the page on which the edit link was clicked. In HTML, such a link would look like this: