JavaScript XMLHttpRequest.onreadystatechange

Question

我正在尝试做一些AJAX,并且需要知道为什么这段代码没有触发完成或错误警报.我在Mozilla Firefox 20.0.1中

请注意

此代码IS更新数据库(我有一个select语句读取准确记录验证它的更新),我只是不确定为什么当响应已经完成,我不能得到一个警报.

我有这些GLOBAL(在javascript页面的顶部)声明变量.

var AjaxEnginePage;
var ClientInfoPage;
var XMLHTTP;
AjaxEnginePage = "AjaxEngine.aspx";
ClientInfoPage="getClientInfo.aspx";

创建连接.

 //Creating and setting the instance of appropriate XMLHTTP Request object to a “XmlHttp” variable  
function CreateXMLHTTP()
{
try
{
    XMLHTTP = new ActiveXObject("Msxml2.XMLHTTP");
}
catch(e)
{
    try
    {
        XMLHTTP = new ActiveXObject("Microsoft.XMLHTTP");
    } 
    catch(oc)
    {
        XMLHTTP = null;
    }
}
//Creating object in Mozilla and Safari 
if(!XMLHTTP && typeof XMLHttpRequest != "undefined") 
{
    XMLHTTP = new XMLHttpRequest();
}
}

绑定连接:

function btnUpdateMe_OnClick() {
var me = encodeURIComponent(document.getElementById("MeTextBox").value);  

// construct the URL
var requestUrl = AjaxEnginePage + "?Action=UpdateMe&Me=" + me;

CreateXMLHTTP();

// If browser supports XMLHTTPRequest object
if(XMLHTTP) 
   {
    //Setting the event handler for the response
    XMLHTTP.onreadystatechange = handleStateChange(me);

    //Initializes the request object with GET (METHOD of posting), 
    //Request URL and sets the request as asynchronous.
    XMLHTTP.open("get", requestUrl,  true);

    //Sends the request to server
    XMLHTTP.send(null);     
}

处理国家变化

 function handleStateChange(me) {
  switch (XMLHTTP.readyState) {
    case 0: // UNINITIALIZED
    case 1: // LOADING
    case 2: // LOADED
    case 3: // INTERACTIVE
        break;
    case 4: // COMPLETED
        alert("Success");
        break;
    default: alert("error");
 }

如果需要,我可以提供更多代码.:( 谢谢.

Answer 1

更改:

XMLHTTP.onreadystatechange = handleStateChange(me);

至:

XMLHTTP.onreadystatechange = function() {handleStateChange(me);};

您正在设置onreadystatechange调用函数的结果,而不是函数.