function ajax_call(){
	var xmlhttp;
   // code for IE7+, Firefox, Chrome, Opera, Safari
		if (window.XMLHttpRequest)
		{
		// code for IE7+, Firefox, Chrome, Opera, Safari
			xmlhttp=new XMLHttpRequest();
		}
		else if (window.ActiveXObject)
		{
		// code for IE6, IE5
			xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
		}
		else
		{
			alert("Your browser does not support XMLHTTP!");
		}	
		return xmlhttp;
}

function trim (str, charlist) {    
 
    var whitespace, l = 0, i = 0;
    str += '';
    
    if (!charlist) {
        // default list
        whitespace = " \n\r\t\f\x0b\xa0\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u200b\u2028\u2029\u3000";
    } else {
        // preg_quote custom list
        charlist += '';
        whitespace = charlist.replace(/([\[\]\(\)\.\?\/\*\{\}\+\$\^\:])/g, '$1');
    }
    
    l = str.length;
    for (i = 0; i < l; i++) {
        if (whitespace.indexOf(str.charAt(i)) === -1) {
            str = str.substring(i);
            break;
        }
    }
    
    l = str.length;
    for (i = l - 1; i >= 0; i--) {
        if (whitespace.indexOf(str.charAt(i)) === -1) {
            str = str.substring(0, i + 1);
            break;
        }
    }
    
    return whitespace.indexOf(str.charAt(0)) === -1 ? str : '';
}

function validate_required(field,alerttxt)
{
with (field)
  {
  if (value==null|| trim(value,'')=="")
    {
    alert(alerttxt);return false;
    }
  else
    {
    return true;
    }
  }
}