gistfile1.js

has.add("activex", typeof ActiveXObject != "undefined");

getXhr = function(){
	throw new Error("XMLHttpRequest is unavailable");
};
if(has("native-xhr") && !has("dojo-force-activex-xhr")){
	getXhr = function(){
		return new XMLHttpRequest();
	};
}else if(has("activex")){
	var XMLHTTP_PROGIDS = ['Msxml2.XMLHTTP', 'Microsoft.XMLHTTP'], progid,
		_getXhr = function(){
			return new ActiveXObject(progid);
		};
	i = 0;
	// if in the browser an old IE; find an xhr
	while(i<2){
		try{
			progid = XMLHTTP_PROGIDS[i++];
			if(new ActiveXObject(progid)){
				// this progid works; therefore, use it from now on
				getXhr = _getXhr;
				break;
			}
		}catch(e){
			// squelch; we're just trying to find a good ActiveX progid
			// if they all fail, then progid ends up as the last attempt and that will signal the error
			// the first time the client actually tries to exec an xhr
		}
	}
}
req.getXhr = getXhr;