Javascript Ajax 请求

    var XMLHttpReq;  
    function createXMLHttpRequest() {  
        try {  
            XMLHttpReq = new ActiveXObject("Msxml2.XMLHTTP");//IE高版本创建XMLHTTP  
        }  
        catch(E) {  
            try {  
                XMLHttpReq = new ActiveXObject("Microsoft.XMLHTTP");//IE低版本创建XMLHTTP  
            }  
            catch(E) {  
                XMLHttpReq = new XMLHttpRequest();//兼容非IE浏览器，直接创建XMLHTTP对象  
            }  
        }  
      
    }  
    function sendAjaxRequest(url) {  
        createXMLHttpRequest();                                //创建XMLHttpRequest对象  
        XMLHttpReq.open("post", url, true);  
        XMLHttpReq.onreadystatechange = processResponse; //指定响应函数  
        XMLHttpReq.send(null);  
    }  
    //回调函数  
    function processResponse() {  
        if (XMLHttpReq.readyState == 4) {  
            if (XMLHttpReq.status == 200) {  
                var text = XMLHttpReq.responseText;  
      
                /** 
                 *实现回调 
                 */  
                text = window.decodeURI(text);  
                var cp = document.getElementById("cp");  
                cp.innerHTML = "";  
                var values = text.split("|");  
                for (var i = 0; i < values.length; i++) {  
                    var temp = document.createElement("option");  
                    temp.text = values[i];  
                    temp.value = values[i];  
                    cp.options.add(temp);  
                }  
      
      
            }  
        }  
      
    }