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Publishing AJAX and PHP - part 24

AJAX RSS Reader return xmlHttp; } // function that displays an error message function displayError($message) { // ignore errors if showErrors is false if (showErrors) { // turn error displaying Off showErrors = false; // display error message alert("Error encountered: \n" + $message); } } // Retrieve titles from a feed and display them function getFeed(feedLink, feed) { // only continue if xmlHttp isn't void if (xmlHttp) { // try to connect to the server try { if (xmlHttp.readyState == 4 || xmlHttp.readyState == 0) { /* Get number of feeds and loop through each one of them to change. | AJAX RSS Reader return xmlHttp function that displays an error message function displayError message ignore errors if showErrors is false if showErrors turn error displaying Off showErrors false display error message alert Error encountered n message Retrieve titles from a feed and display them function getFeed feedLink feed only continue if xmlHttp isn t void if xmlHttp try to connect to the server try if xmlHttp.readyState 4 xmlHttp.readyState 0 Get number of feeds and loop through each one of them to change the class name of their container li . var numberOfFeeds document.getElementByld feedList .childNodes.length for i 0 i numberOfFeeds i document.getElementByld feedList .childNodes i .className Change the class name for the clicked feed so it becomes highlighted feedLink.className active Display Loading. message while loading feed document.getElementByld loading .style.display block Call the server page to execute the server-side operation params feed feed xmlHttp.open POST rss_reader.php true xmlHttp.setRequestHeader Content-Type application x-www-form-urlencoded xmlHttp.onreadystatechange handleHttpGetFeeds xmlHttp.send params else if connection was busy try again after 1 second setTimeout getFeed feedLink feed 1000 display the error in case of failure catch e displayError e.toString function that retrieves the HTTP response function handleHttpGetFeeds 230 Chapter 9 continue if the process is completed if xmlHttp.readyState 4 continue only if HTTP status is OK if xmlHttp.status 200 try displayFeed catch e display error message di splayError e .toString else displayError xmlHttp.statusText Processes server s response function displayFeed read server response as text to check for errors var response xmlHttp.responseText server error if response.indexOf ERRNO 0 response.indexOf error 0 response.length 0 throw response.length 0 Void server response. response hide the Loading. message upon feed retrieval document.getElementByld loading .style.display none append