In this tutorial, you will learn how to retrieve specific header information from a file/resource.
Ajax retrieve specific header
In this tutorial, you will learn how to retrieve specific header information from a file/resource. This can be done using getResponseHeader() function. This function() returns the specific header information of a resource/ file like length, server-type, content-type, last-modified, etc.
Example
In this example, we will fetch the Last-Modified header information of the TextDocument.txt.
retrievespecificheader.php
<html>
<head>
<script type="text/javascript">
function loadXMLDoc(url)
{
var xmlhttp;
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById('p1').innerHTML="Last modified: "
+ xmlhttp.getResponseHeader('Last-Modified');
}
}
xmlhttp.open("GET",url,true);
xmlhttp.send();
}
</script>
</head>
<body>
<p id="p1">Click the below button to fetch the header onformation of the
TextDocument.txt file.</p>
<button onclick="loadXMLDoc('TextDocument.txt')">Get "Last-Modified" information
</button>
</body>
</html>
Output :
When you click on the button :
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