// JavaScript Document
function getRequest() {

        http_request = false;
        if (window.XMLHttpRequest) {
                //对于Mozilla、Netscape、Safari等浏览器，创建XMLHttpRequest
                http_request = new XMLHttpRequest();
                if (http_request.overrideMimeType) {
                        //如果服务器响应的header不是text/xml，可以调用其它方法修改该header
                        http_request.overrideMimeType('text/xml');
                }
        } else if (window.ActiveXObject) {
                // 对于Internet Explorer浏览器，创建XMLHttpRequest
                try {
                        http_request = new ActiveXObject("Msxml2.XMLHTTP");
                } catch (e) {
                        try {
                                http_request = new ActiveXObject("Microsoft.XMLHTTP");
                        } catch (e) {}
                }
        }
        return http_request;
}

//POST 提交数据
function posthttp(str,url){
        http_request=getRequest();
        http_request.open('POST',url,false);
        http_request.setRequestHeader("Content-Length",str.length);
        http_request.setRequestHeader("CONTENT-TYPE","application/x-www-form-urlencoded");

        http_request.send(str);
        if (http_request.readyState == 4)
        {
        　　　// 收到完整的服务器响应
        　　　if (http_request.status == 200) {
                        //HTTP服务器响应的值OK
                　　　  requestdoc = http_request.responseText;
                　　　  //将服务器返回的字符串写到页面中ID为message的区域
                        return requestdoc;
        }else{
        　　　　  //requestdoc = http_request.status;
                return false;
        　　 }
        }
}