For simplicity and clarity, I will only test it in HTML; I will not talk nonsense if I write it clearly in annotations;
Many companies may prevent you from using any Ajax framework to implement the Ajax effect during the interview. Although this code looks painful, there is no other way, you can also remember it if you don't remember it (in fact, it's not that difficult to remember it ......)
Readystate indicates the processing status of the XMLHTTPRequest object: 0: the XMLHTTPRequest object has not been initialized yet. 1: the XMLHTTPRequest object starts sending requests. 2: The request of the XMLHTTPRequest object is sent completely. 3: the XMLHTTPRequest object starts to read the server's response. 4: the XMLHTTPRequest object reads the server and the response ends.
<! Doctype HTML public "-// W3C // dtd xhtml 1.0 transitional // en" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
XMLHTTP. Open ("Post", "getdate. ashx", false); // you are going to send a POST request to the getdate. ashx (General handler) of the server.
// XMLHTTP is not a synchronous request by default (also recommended), that is, the open method does not return the data returned by the server as the downloadstring of WebClient. It is asynchronous, therefore, the onreadystatechange event must be monitored anonymously;
XMLHTTP. onreadystatechange = function (){
If (XMLHTTP. readystate = 4) {// If the XMLHTTPRequest object reads the server, the response ends;
If (XMLHTTP. Status = 200) {// If the status code is 200, the processing is successful;
Document. getelementbyid ("getdate"). value = XMLHTTP. responsetext; // The responsetext attribute is the text returned by the server.
} Else {
Alert ("ajax server return error ");
}
}
}
XMLHTTP. Send (); // The request starts to be sent.
}
</SCRIPT>
</Head>
<Body>
<Input id = "getdate" type = "text"/>
<Input type = "button" value = "request time" onclick = "btnclick ()"/>
</Body>
</Html>
Getdate. ashx (General handler) code:
Using system;
Namespace Ajax
{
/// <Summary>
/// Getdate: Get the server time
/// </Summary>
Public class getdate: ihttphandler
{
Public void processrequest (httpcontext context)
{
Context. response. contenttype = "text/plain ";
Context. response. Write (datetime. Now. tostring ());
}
Public bool isreusable
{
Get
{
Return false;
}
}
}
}
Start building with 50+ products and up to 12 months usage for Elastic Compute Service
1 on 1 presale consultation
24/7 Technical Support 6 Free Tickets per Quarter Faster Response
Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.
A comprehensive suite of global cloud computing services to power your business
Payment Methods We Support
