var url="http://www.china-merchandise.biz/populate_tab.php";
  var tabbid ="";
  
  function poupulateTab(tabid){
      tabbid = tabid;
      xmlhttpPost(url, tabid);
  }
 
  function xmlhttpPost(strURL, tabid) {
     
      var xmlHttpReq = false;
      var self = this;
      // Mozilla/Safari
      if (window.XMLHttpRequest) {
          self.xmlHttpReq = new XMLHttpRequest();
      }
      // IE
      else if (window.ActiveXObject) {
          self.xmlHttpReq = new ActiveXObject("Microsoft.XMLHTTP");
      }
      self.xmlHttpReq.open('POST', strURL, true);
      self.xmlHttpReq.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
      self.xmlHttpReq.onreadystatechange = function() {
          if (self.xmlHttpReq.readyState == 4) {
              updatepage(self.xmlHttpReq.responseText);
          }
      }
      self.xmlHttpReq.send(getquerystring(tabid));
  }
  
  function getquerystring(tabid) {
      //var form = document.forms['search_form'];
      //var word = form.sub_directories_search.value;
      //alert(tabid);
      qstr = 'tab=' + escape(tabid);  // NOTE: no '?' before querystring
      return qstr;
  }
  
  function updatepage(str){
      document.getElementById("tab"+tabbid).innerHTML = str;
  }