ajax基本通用代碼示例

html>
head>
script type="text/JavaScript">
var xmlhttp
function loadXMLDoc(url)
{
 // code for Mozilla, etc.
 if (window.XMLHttpRequest)
 {
 xmlhttp=new XMLHttpRequest()
 xmlhttp.onreadystatechange=state_Change
 xmlhttp.open("GET",url,true)
 xmlhttp.send(null)
 }
 // code for IE
 else if (window.ActiveXObject)
 {
 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP")
  if (xmlhttp)
  {
  xmlhttp.onreadystatechange=state_Change
  xmlhttp.open("GET",url,true)
  xmlhttp.send()
  }
 }
}
function state_Change()
{
 // if xmlhttp shows "loaded"
 if (xmlhttp.readyState==4)
 {
 // if "OK"
 if (xmlhttp.status==200)
 {
 document.getElementById('T1').innerHTML=xmlhttp.responseText
 }
 else
 {
 alert("Problem retrieving data:" + xmlhttp.statusText)
 }
 }
}
/script>
/head>
body onload="loadXMLDoc('test_xmlhttp.txt')">
div id="T1" style="border:1px solid black;height:40;width:300">/div>br />
button onclick="loadXMLDoc('test_xmlhttp2.txt')">Click/button>
/body>
/html>