通过 XML HTTP 进行一次指定的报头（HEAD）请求 (JavaScript)

编辑下面的代码，然后点击查看运行效果按钮，右侧显示代码修改后的运行结果

<html>
<head>
<script type="text/javascript">
var xmlhttp

function loadXMLDoc(url)
{
xmlhttp=null
// code for Mozilla, etc.
if (window.XMLHttpRequest)
  {
  xmlhttp=new XMLHttpRequest()
  }
// code for IE
else if (window.ActiveXObject)
  {
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP")
  }
if (xmlhttp!=null)
  {
  xmlhttp.onreadystatechange=state_Change
  xmlhttp.open("GET",url,true)
  xmlhttp.send(null)
  }
else
  {
  alert("Your browser does not support XMLHTTP.")
  }
}

function state_Change()
{
// if xmlhttp shows "loaded"
if (xmlhttp.readyState==4)
  {
  // if "OK"
  if (xmlhttp.status==200)
  {
  document.getElementById('T1').innerHTML="This file was last modified on: " + xmlhttp.getResponseHeader('Last-Modified')
  }
  else
  {
  alert("Problem retrieving data:" + xmlhttp.statusText)
  }
  }
}

</script>
</head>

<body onload="loadXMLDoc('/xml/try/xml_test_xmlhttp.txt')">
<p>
With a HEAD request, a server will return the headers of a resource (not the resource itself). This means you can find out the Content-Type or Last-Modified of a document, without downloading it itself.
</p>
<div id="T1" style="border:1px dotted green;height:100;width:500"></div>
</body>

</html>

运行结果:上一个示例：通过 XML HTTP 进行一次报头（HEAD）请求 (JavaScript) 下一个示例：通过 XML HTTP 把 XML 文件显示为 HTML 表格

XML 示例 - W3C HTML - 在线测试工具 V1.0