如何爲此代碼添加自動刷新？

我叫約翰。（是的，我知道非常有用的信息:)）我在PHP中創建一個新的統計數據，我的Javascript代碼看起來像如何爲此代碼添加自動刷新？

var req; 

function hide() { 
    for(var i=0; i<arguments.length; i++) { 
     element = document.getElementById(arguments[i]); 
     if (element) { 
      element.style.visibility = 'hidden'; 
     } 
    } 
} 

function show() { 
    for(var i=0; i<arguments.length; i++) { 
     element = document.getElementById(arguments[i]); 
     if (element) { 
      element.style.visibility = 'visible'; 
     } 
    } 
} 

function loadXMLDoc(url) { 
    if (window.XMLHttpRequest) { 
     req = new XMLHttpRequest(); 
     req.onreadystatechange = processReqChange; 
     req.open("GET", url, true); 
     req.send(null); 

     hide('lastposts'); 
     show('lastposts_update'); 

    } else if (window.ActiveXObject) { 
     req = new ActiveXObject("Microsoft.XMLHTTP"); 
     if (req) { 
      req.onreadystatechange = processReqChange; 
      req.open("GET", url, true); 
      req.send(); 

      hide('lastposts'); 
      show('lastposts_update'); 
     } 
    } 
} 

function processReqChange() { 
    if (req.readyState == 4) { 
     element = document.getElementById('lastposts_text'); 
     if (element) { 
      if (req.status == 200) { 
       element.innerHTML = req.responseText; 
      } else { 
       element.innerHTML = "Error " + req.status + "<br />" + req.statusText; 
      } 
     } 

     hide('lastposts_update'); 
     show('lastposts'); 
    } else { 
     var status_message = new Array(
     "The query is not initialized", 
     "The query is created", 
     "The query is sent", 
     "The query is processed" 
     ); 

     element_status = document.getElementById('status'); 
     if (element_status) { 
      element_status.innerHTML = status_message[req.readyState]; 
     } 
    } 
}

和HTML輸出

<div id="lastposts_update" style="visibility: hidden;"> 
    <img src="images/refresh.gif" alt="wait">&nbsp; 
    <span id="status"></span> 
</div> 

<div id="lastposts" style="z-index: 2;"> 
<a href="" onclick="loadXMLDoc('{URL}'); return false;"> 
<img src="images/refresh.gif" alt="refresh" border="0"></a> 

<span id="lastposts_text"> 
{IMPORT_NEW_STATISTICS} 
</span> 

</div>

如何修改這個代碼，並添加自動刷新和刪除手動刷新？你能幫我嗎？我會很感激

來源

2015-02-08 John