ajax JavaScript XMLHttpRequest.onreadystatechange
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JavaScript XMLHttpRequest.onreadystatechange
提问by Kulingar
I'm attempting to do some AJAX and need to know why this code isn't firing a completed or error alert. I'm in Mozilla Firefox 20.0.1
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
PLEASE NOTE
请注意
This code ISupdating the database (I have a select statement reading the exact record verifying it's updating) I'm just unsure as to why I can't get an alert when the response has completed.
此代码IS更新数据库（我有一个SELECT语句读验证它的更新的确切记录）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。
I have these GLOBAL (at the top of the javascript page) declared variables.
我有这些 GLOBAL （在 javascript 页面的顶部）声明的变量。
var AjaxEnginePage;
var ClientInfoPage;
var XMLHTTP;
AjaxEnginePage = "AjaxEngine.aspx";
ClientInfoPage="getClientInfo.aspx";
Creating the connection.
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();
}
}
Tying the connection:
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);
}
Handle State Change
处理状态变化
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");
}
I can provide more code if needed. :( thanks.
如果需要，我可以提供更多代码。：（ 谢谢。
回答by Barmar
Change:
改变：
XMLHTTP.onreadystatechange = handleStateChange(me);
to:
到：
XMLHTTP.onreadystatechange = function() {handleStateChange(me);};
You're setting onreadystatechangeto the result of calling the function, not to the function.
您设置onreadystatechange的是调用函数的结果，而不是函数。
