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Basic Ajax tutorial (5) _ read Response Header

Source: Internet
Author: User
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<! DOCTYPE html PUBLIC "-// W3C // dtd xhtml 1.0 Strict // EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<Html xmlns = "http://www.w3.org/1999/xhtml">

<Head>

<Title> Reading Response Headers </title>

<Script type = "text/javascript">

Var xmlHttp;

Var requestType = "";

Function createXMLHttpRequest (){
If (window. ActiveXObject ){
XmlHttp = new ActiveXObject ("Microsoft. XMLHTTP ");
} Else if (window. XMLHttpRequest ){
XmlHttp = new XMLHttpRequest ();
}

}

Function doHeadRequest (request, url ){
RequestType = request;
CreateXMLHttpRequest ();
XmlHttp. onreadystatechange = handleStateChange;
XmlHttp. open ("HEAD", url, true );
XmlHttp. send (null );

}

Function handleStateChange (){
If (xmlHttp. readyState = 4 ){
If (requestType = "allResponseHeaders "){
GetAllResponseHeaders ();}
Else if (requestType = "lastModified "){
GetLastModified ();
} Else if (requestType = "isResourceAvailable "){
GetIsResourceAvailable ();
}
}
}

Function getAllResponseHeaders (){
Alert (xmlHttp. getAllResponseHeaders ());

}

Function getLastModified (){
Alert ("Last Modified:" + xmlHttp. getResponseHeader ("Last Modified :"));

}

Function getIsResourceAvailable (){
If (xmlHttp. status = 200 ){
Alert ("Successful response ");}
Else if (xmlHttp. status = 404 ){
Alert ("Resource is unavailable ");}
Else {
Alert ("Unexpected response status:" + xmlHttp. status );
}
}
</Script>

</Head>

<Body> <A href = "javascript: doHeadRequest ('allresponseheaders', 'readingresponseheaders. xml');"> Read All Response Headers </a> <br/>
<A href = "javascript: doHeadRequest ('lastmodified', 'readingresponseheaders. xml');"> Get Last Modified Date </a> <br/>
<A href = "javascript: doHeadRequest ('isresourceavailable', 'readingresponseheaders. xml');"> Read Available Resource </a> <br/>
<A href = "javascript: doHeadRequest ('isresourceavailable', 'not-available. xml');"> Read Unavailable Resource </a>

</Body>

</Html>

 

ReadingResponseHeaders. xml file

 

<? Xml version = "1.0" encoding = "UTF-8"?>

<ReadingResponseHeaders>

</ReadingResponseHeaders>

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