function createXHR () {
if (typeof XMLHttpRequest != "undefined") {
return new XMLHttpRequest();
} else if (window.ActiveObject) {
var aVersions = [ " MSXML2.XMLHttp.6.0", "MSXML2.XMLHttp.3.0"];
for (var i = 0; i < aVersions.length; i++) {
try {
var oXHR = new ActiveXObject(aVersions[i]);
return oXHR;
} catch (oError) {
//Do nothing
}
}
}
throw new Error("XMLHttp object could not be created.");
}
参考《Ajax高级程序设计》(第2版)P32