New to me at least. Anthony posted about an http 204 trick on Amazon. To see it in action, go the the "Improve your recommendations" section, and then to the page where you rate books. Try giving a book a star rating using the mouseover imagemap - notice that there's a momentary browser submission, and the page now says "Saved" - but the page didn't rebuild. A co-worker and I looked into this a little one day and couldn't figure it out. After reading Anthony's post I went back and looked at the source again...here's the relevant javascript function: function amz_js_sendRating(asin, ratingType, ratingValue) { amz_js_restoreDefaultMessage(asin); var submitURL = '' + '/exec/obidos/instant-recs/102-4930794-1634500?' + 'rating.source=ir' + '&rating.asin.1=' + asin + '&use-new-form=true' + '&return.index.begin=1' + '&rating.' + ratingType + '.1=' + ratingValue + '¬-interested=1' + '&template-name=' + encodeURIComponent( 'stores/recs/ratings/rate-asin-return-page'); if ( ( ( ratingType == 'onetofive' ) || ( ratingType == 'owned' ) ) && ( savedNotInterested[asin] == 1 ) ) { submitURL = submitURL + '&rating.notinterested.1=NONE'; savedNotInterested[asin] = 0; } else if ( ratingType == 'notinterested' ) { if ( savedRatings[asin] > 0 ) { submitURL = submitURL + '&rating.onetofive.1=NONE'; savedRatings[asin] = 0; } if ( savedIsOwned[asin] == 1 ) { submitURL = submitURL + '&rating.owned.1=NONE'; savedIsOwned[asin] = 0; } } window.location.href = submitURL + "&return.response=204"; window.setTimeout( "amz_js_swapThankYouMessage('"+asin+"')", delayTime); } Note that they reset the window href, and send a signal to the server to send an http 204 to the browser. I found the spec entry on http 204: RFC 1945 - Hypertext Transfer Protocol -- HTTP/1.0: 204 No Content The server has fulfilled the request but there is no new information to send back. If the client is a user agent, it should not change its document view from that which caused the request to be generated. This response is primarily intended to allow input for scripts or other actions to take place without causing a change to the user agent's active document view. The response may include new metainformation in the form of entity headers, which should apply to the document currently in the user agent's active view. So in short, you can submit information to the server and not have to do a page rebuild. Which is a nice trick for functionality like in the Amazon example - they have a "Saved" message that they make appear so the user knows something happened....
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