Creating XMLHttpRequest Objects

Creating XMLHttpRequest Objects

In most browsers, XMLHttpRequest is a standard Javascript class, so you just create a new instance XMLHttpRequest. However, Microsoft were the inventors of XMLHttpRequest, and until IE7, IE only offered as an ActiveX object. To make things even more fun, there are different versions of that object. The following code shows a factory function that works on all browsers that support XMLHttpRequest.

function createXMLHttpRequest() {
try { return new XMLHttpRequest(); } catch(e) {}
try { return new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) {}
try { return new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) {}
alert("XMLHttpRequest not supported");
return null;
}
...
var xhReq = createXMLHttpRequest();