解决Ajax不支持火狐！

			function getOs()   
				{   
				   var OsObject = "";   
				   if(navigator.userAgent.indexOf("MSIE")>0) {   
				        return "MSIE";       //IE浏览器
				   }
				   if(isFirefox=navigator.userAgent.indexOf("Firefox")>0){   
				        return "Firefox";     //Firefox浏览器
				   }
				   if(isSafari=navigator.userAgent.indexOf("Safari")>0) {   
				        return "Safari";      //Safan浏览器
				   }
				   if(isCamino=navigator.userAgent.indexOf("Camino")>0){   
				        return "Camino";   //Camino浏览器
				   }
				   if(isMozilla=navigator.userAgent.indexOf("Gecko/")>0){   
				        return "Gecko";    //Gecko浏览器
				   }   
				} 


			function addTravellerByAjaxNew2() {	
				var str=document.getElementById('rand2').value;
				var btype=getOs();
				if(btype!="Firefox"){
					http_request = new ActiveXObject("Microsoft.XMLHTTP");
				}else{
					http_request =new XMLHttpRequest();
				}
				http_request.open("POST", "<%=basePath%>servlet/RandImgCheck?type=1&rand2="+str, true);
				http_request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
				http_request.send(null);
				http_request.onreadystatechange = (btype!="Firefox")?(showTravellerPageNew2):(showTravellerPageNew2());
			}
			function showTravellerPageNew2() {
			var travellerText;
				alert("Welcome!");
				if (http_request.readyState == 4) {
					
					if (http_request.status == 200) {				
						travellerText = http_request.responseText;
						if(travellerText=='1'){
						document.forms[0].submit();
						}else{
						alert("验证码输入错误");
						reloadcode2();
						
						}
					}
				}
			}
</script>