一段兼容IE和FF的Ajax程序

var id;

function retrieveURL(url,sid){
        //调用AJAX
        id = sid;
        if (window.XMLHttpRequest) {
            // 非IE浏览器
            req = new XMLHttpRequest();
            req.onreadystatechange = processStateChange;
            
            try {
                req.open("GET", url, true);
            } catch (e) {
            alert("Server Communication Problem/n"+e);
            }
            req.send(null);
        } else if (window.ActiveXObject) {
            // IE
            req = new ActiveXObject("Microsoft.XMLHTTP");
            
            if (req) {
                req.onreadystatechange=processStateChange;
                req.open("GET", url, true);
                req.send();
            }
    
        }
    }

    function processStateChange() {
        if (req.readyState == 4) { // 完成
            if (req.status == 200) { // 响应正常
                //将响应的文本分割成Span元素
                //alert(id+"/n"+req.responseText);
                document.getElementById(id).innerHTML = req.responseText;
                
            } else {
                alert("Problem with server response:/n "+ req.statusText);
            }
        }
    }
//兼容IE和FF，程序来源：hqin6