XMLHttpRequest object methods and attributes and AJAX standard implementation examples

The methods and attributes of the XMLHttpRequest object are listed below, marked in red as the most likely

Related methods:

Abort () stops the current request

GetAllResponseHeaders () returns all HTTP Request Response Headers as key/value pairs.

GetResponseHeader ("header") returns the string value of the specified header.

Open ("method", "url") creates a call to the server.

Send (content) sends a request to the server

SetRequestHeader ("header", "value") sets the specified header to the provided value. You must call open () before setting any header ()

Related attributes:

This event processor is triggered when the onreadystatechange status changes. Generally, a JavaScript function is called.

ReadyState Request status 0 = not initialized, 1 = loading, 2 = loaded, 3 = interaction, 4 = completed

ResponseText server response, which is a string

The response of the responseXML server, expressed as XML. This object can be parsed as a DOM object.

Status Server HTTP status code (200 corresponds to OK, 404 corresponds to Not Found (Not Found ),

Corresponding text of statusText HTTP status code (OK or Not Found (Not Found)

A standard XMLHttpRequest object to implement ajax

<Script type = "text/javascript">
Var xmlHttp;

// Function 1: Create an XMLHttpRequest object

Function createXMLHttpRequest (){

// Different IE versions

If (window. ActiveXObject ){

Try {xmlHttp = new ActiveXObject ("Msxml2.XMLHTTP ");}

Catch (e) {xmlHttp = new ActiveXObject ("Microsoft. XMLHTTP ");}

}

// Non-IE

Else if (window. XMLHttpRequest ){

XmlHttp = new XMLHttpRequest ();

}

}
// Function 2: The function to be called

Function startRequest (){

CreateXMLHttpRequest ();

Var url = "XXX. ashx? "+ New Date (). getTime ();

XmlHttp. onreadystatechange = handleStateChange;

XmlHttp. open ("GET", url, true );

XmlHttp. send (null );

}

// Function 3: The Event function triggered when the status changes

Function handleStateChange (){

If (xmlHttp. readyState = 4 ){

If (xmlHttp. status = 200 ){

Var result = xmlHttp. responseText;

Document. getElementById ("validateMessage"). innerText = result;

}

}

}

</Script>