Comet - High Speed AJAX
June 12th, 2007
Basic Definitions of Comet:
Wiki
Server Technologies:
IE will not allow your to read xmlhttp.responseText untill xmlhttp.readyState = 4 (complete — connection closed). It works in FF.
var http_request = false; function makeRequest(url) { http_request = false; if (window.XMLHttpRequest) { // Mozilla, Safari,... http_request = new XMLHttpRequest(); if (http_request.overrideMimeType) { http_request.overrideMimeType('text/xml'); // See note below about this line } } else if (window.ActiveXObject) { // IE try { // http_request = new ActiveXObject("Msxml2.XMLHTTP"); http_request = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) { try { http_request = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) {} } } if (!http_request) { alert('Giving up :( Cannot create an XMLHTTP instance'); return false; } http_request.onreadystatechange = alertContents; http_request.open('GET', url, true); http_request.send(null); } var i = 0; var str = ""; function alertContents() { $('info').innerHTML = '<h3>'+ Date() + ' ' + http_request.readyState +':</h3>' + http_request.responseText; if (http_request.readyState == 4) { $('info').innerHTML = '<h1>Complete ('+ http_request.status +'):</h1>' + http_request.responseText; } } function $() { var elements = new Array(); for (var i = 0; i < arguments.length; i++) { var element = arguments[i]; if (typeof element == 'string') { if (document.getElementById) { element = document.getElementById(element); } else if (document.all) { element = document.all[element]; } } elements.push(element); } if (arguments.length == 1 && elements.length > 0) { return elements[0]; } else { return elements; } } function go(){ makeRequest('http://www.kevincornwell.com/comet/x-mixed-replace.php'); }
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