function getXmlHttpObject() {
  var xmlhttp;
  
  /*@cc_on
  @if (@_jscript_version >= 5 ) 
    try {
      xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
    } catch( e ) {
      try {
         xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
      } catch( ee ) {
        xmlhttp = false;
      }
    }
  @else
    xmlhttp = false;
  @end @*/
  if ( !xmlhttp && typeof XMLHttpRequest != 'undefined' ) {
    try {
      xmlhttp = new XMLHttpRequest();
      xmlhttp.overrideMimeType("text/xml");
    } catch(e) {
      xmlhttp = false;
    }
  }
  
  return xmlhttp;
}

var xmlHttp = getXmlHttpObject();

function setTenki() {
  if ( xmlHttp.readyState == 4 && xmlHttp.status == 200 ) {
    var xmlDoc = xmlHttp.responseXML;
    if ( xmlDoc.documentElement ) {
      var tenki = xmlDoc.getElementsByTagName('tenki').item(0).firstChild;
      if ( tenki != null ) document.getElementById('tenki').innerHTML = tenki.data;
    } else {
      document.getElementById('tenki').innerHTML = "";
    }
  }
}

function getTenki() {
  xmlHttp.open('GET',"tenki.php",true);
  xmlHttp.onreadystatechange = setTenki;
  xmlHttp.send(null);
}

getTenki();