/** * Global instance of request object */ var http_request = null; var ajax_request_queue = new Array(); /** * ajax_init() * Initialise AJAX to be called inside */ function ajax_init() { create_http_request_object(); } /** * create_http_request_object() * Create a new instance of the HTTP request object with * cross-browser support */ function create_http_request_object() { var ro = null; if(window.ActiveXObject) { ro = new ActiveXObject("Microsoft.XMLHTTP"); } else { ro = new XMLHttpRequest(); } if(ro==null) { alert("Error: Your browser does not support the necessary functionality. (Create HRO)"); } http_request = ro; return ro; } /** * http_request_exists() * Returns true if http_request global instance exists * and is set */ function http_request_exists() { if(http_request==null) { http_request = create_http_request_object(); if(http_request==null) { alert("Error: Your browser does not support the necessary functionality. (Use HRO)"); return false; } } return true; } /** * get_http_response_text() * Returns the response as plain text/plain */ function get_http_response_string() { return http_request.responseText; } /** * get_http_response_text() * Returns the response as text/xml */ function get_http_response_xml() { return http_request.responseXML; } /** * response_exists() * Returns true if the server response is waiting and * there is no error in the response */ function http_response_exists() { if(http_request_exists() && (http_request.readyState==4) && (http_request.status==200)) { handle_response_error(); return true; } return false; } /** * push_request(url, callback_function) * Push a new request into the HTTP request queue. Note that * all requests are send via HTTP GET */ function push_request(url, callback_function) { if(document.getElementById("waiting")) { document.getElementById("waiting").style.display = 'block'; if(document.getElementById("portfolio_image")) document.getElementById("portfolio_image").innerHTML = ''; } var new_request = new Array(); new_request[0] = url; new_request[1] = callback_function; ajax_request_queue.push(new_request); setTimeout("shift_request();", 100); } /** * shift_request() * Shift a request from the queue when the request object is * ready */ function shift_request() { if((http_request.readyState==4 || http_request.readyState==0) && ajax_request_queue.length > 0) { var request = ajax_request_queue.shift(); http_request.open('GET', request[0], true); http_request.onreadystatechange = request[1]; http_request.send(null); } return true; } /** * handle_response_error() * Support function for response_exists() - will alert server * response error */ function handle_response_error() { var response = http_request.responseText; if((response.indexOf('AJAX_ERROR')>=0) || (response.length==0)) { alert("Error: Server response produced an exception or does not exist:\n\n"+response); } } /** * load_xslt(xslt_path) * Load XSLT document synchronously from server * given the .xsl path. Returns XSLT doc object */ function load_xslt(xslt_path) { var xslt_doc_tmp = null; if(http_request_exists()) { http_request.open("GET", xslt_path, false); http_request.send(null); if(this.DOMParser) { var dp = new DOMParser(); xslt_doc_tmp = dp.parseFromString(http_request.responseText, "text/xml"); } else if(window.ActiveXObject) { xslt_doc_tmp = create_msxml_to_document_object(); xslt_doc_tmp.async = false; xslt_doc_tmp.load(http_request.responseXML); } if(xslt_doc_tmp==null) { alert("Error: Failed to load synchronous XSLT via HRO\n(Your browser does not support the necessary functionality)"); } xslt_doc = xslt_doc_tmp; return xslt_doc_tmp; } return false; } /** * create_msxml_to_document_object() * Create a Microsoft XML to DOM document object which allows * the processing of XSTL */ function create_msxml_to_document_object() { var msxml_2_dom; var msxml_2_dom_document_versions = new Array("Msxml2.DOMDocument.6.0", "Msxml2.DOMDocument.5.0", "Msxml2.DOMDocument.4.0", "Msxml2.DOMDocument.3.0"); for(var i=0; i