Ajax and ASP.net no refresh detect if the username exists

/*
1,url is to link the page and pass the past value, pass the past value, let dynamic page execution
2,default.asp tutorial x is the page to be executed for this
3,name is the name of the argument that passed.
4,document.getelementbyid (' Text1 '). Value passing past parameter values
5,message.responsetext the message returned from the server after success
*/

jquery Code

$ (document). Ready (function () {
$ ("#button1"). Click (function () {
$.ajax ({
Type: "Get",
URL: "responsepage.asp tutorial X?name=" +document.getelementbyid (' Text1 '). Value,
Success:function (message) {
alert (message);
}

});

});
});

asp.net tutorial files

if (request["name"]!= null)
{
This.response.clear ();
String name = request["Name"].tostring ();
if (name = = "1")
{
Response.Write ("Username already exists, please fill in other username!");
}
Else
{
Response.Write ("The user name is not registered, you can use!");
}

This.response.end ();
}

JavaScript Tutorial Script file

var ajax = function (option)
{
var request;
var createrequest = function ()
{
var request;
if (window.xmlhttprequest)
{
Request = new XMLHttpRequest ();
}
Else
{
Try
{
Request = new ActiveXObject ("Microsoft.XMLHTTP");
}
catch (E)
{
Request = new ActiveXObject ("Msxml2.xmlhttp");
}
}
return request;
}
var sendrequest = function ()
{
Request = Createrequest ();
Request.open ("Get", Option.url, True);
Request.open ("Post", Option.url, True);
Set this property before sending a request to get ready status on the server
Request.onreadystatechange = Responserequest; Www.111cn.net
Request.send (NULL);
}

var responserequest = function ()
{
Alert ("Ready state of http:" +request.readystate);
if (request.readystate = 4)
{
if (Request.status = 200)
{
Alert ("All goes well!");
Option.success (Request);
}
Else
{
Alert ("An error occurred, the error message is:" +request.status);
Option.failure (Request);
}
}
}
SendRequest ();
}
Determine if the value entered exists
function Getis ()
{
var option =
{
URL: "Default.aspx?name=" +document.getelementbyid (' Text1 '). Value,
Success:function (Message)
{
alert (Message.responsetext);
}
};
New Ajax (option);
}

/*---------The difference between get and post------------
1, get is to add the parameter data queue to submit the form of the action attribute refers to the URL, the value and the form of each field one by one corresponding, in the URL can be seen.
Post is the HTTP post mechanism that places the fields in the form and their contents in the HTML header to the URL address that the action attribute refers to. This process is not visible to the user.
2, for Get way, the server end uses Request.QueryString to obtain the value of the variable,
For post methods, the server side uses Request.Form to obtain the submitted data.
The parameters of both methods can be obtained by request.
3. The amount of data transferred by get is less than 2KB.
Post transfers have a large amount of data, which is generally default to unrestricted.
4, get security is very low, post security is high.
5. When we submit the form, we usually use post, when we want to send a large data file, we need to use post.
When the value passed is only in parameter mode (this value is not more than 2KB), you can use Get method.
/*
Request.readystate = 4 indicates that the server has received a response
Request.status = = 200,http The state value of the server response, indicating that everything is going well
Ready status of HTTP
0: The request was not issued (before calling open ()).
1: The request has been established but has not been issued (before send () is called).
2: The request has been sent out in process (it is usually possible to get the content head from the response).
3: The request has been processed and there is usually some data available in the response, but the server has not completed the response yet.
4: The response is complete, you can access the server response and use it.
*/