Ajax代码

function GetXmlHttpObject() {
    var xmlHttp = null;
    try {
        // Firefox, Opera 8.0+, Safari
        xmlHttp = new XMLHttpRequest();
    }
    catch (e) {
        // Internet Explorer
        try {
            xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
        }
        catch (e) {
            xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
    }
    return xmlHttp;
}

function GetInfo() {

    var xmlHttp = GetXmlHttpObject();

    if (xmlHttp == null) {
        alert("您的浏览器不支持AJAX！");
        return;
    }

    var keystr = document.getElementById("keyword").value;

    var url = "InfoService.aspx";
    url += "?key=" + encodeURI(keystr);
    url += "&type=" + tempType;
    url = url + "&r=" + Math.random();

    xmlHttp.onreadystatechange = function() {
        if (xmlHttp.readyState == 4) {
            //                 try {
            var f = xmlHttp.responseText;
            ShowMsg(f);
            //                 }
            //                 catch (ex) {
            //                     alert("发生意外错误:"+ex);

            //                 }
        }
    };
    xmlHttp.open("GET", url, true);
    xmlHttp.send(null);
}