function ajax_switch(url,target)
{

    if (document.getElementById(target).innerHTML != '')
    {
        document.getElementById(target).innerHTML = '';
    }
    else
    {

        ajax_execute(url,target);
    }

}
function ajax_execute(url,target) 
{
    	// native XMLHttpRequest object
        //document.getElementById(target).innerHTML = '<span class="ajax_waiting"><a href="java script:ajax_execute(\''+url+'\',\''+target+'\');">Sending...</a></span>';
    	if (window.XMLHttpRequest) 
	{
        	req = new XMLHttpRequest();
        	req.onreadystatechange = function() {ajax_Done(target);};
        req.open("GET", url, true);
        req.send(null);
    	// IE/Windows ActiveX version
    	} 
	else if (window.ActiveXObject) 
	{
        	req = new ActiveXObject("Microsoft.XMLHTTP");
        	if (req) 
		{
            		req.onreadystatechange = function() {ajax_Done(target);};
            		req.open("GET", url, true);
            		req.send();
        	}
    	}
}    

function ajax_Done(target) 
{
	// only if req is "loaded"
	if (req.readyState == 4) 
	{
        	// only if "OK"
        	if (req.status == 200) 
		{
            		results = req.responseText;
            		document.getElementById(target).innerHTML = results;
        	} 
		else 
		{
            		document.getElementById(target).innerHTML="Ajax error:\n" + req.statusText;
        	}
    	}
}

function lookup_course(v)
{
	var cid = v.value;
	ajax_execute('includes/ajax/course-description.php?id=' + cid, 'description-box');
}

function submitenter(myfield,e)
{
	var keycode;
	if (window.event) keycode = window.event.keyCode;
	else if (e) keycode = e.which;
	else return true;

	if (keycode == 13)
   	{
		myfield.form.submit();
   		return false;
   	}
	else
   		return true;
}

function confirm_delete()
{
	if (confirm("Really delete this?")==true)
    		return true;
  	else
    		return false;
}

function vIE(){return (navigator.appName=='Microsoft Internet Explorer')?parseFloat((new RegExp("MSIE ([0-9]{1,}[.0-9]{0,})")).exec(navigator.userAgent)[1]):-1;}

function isie6()
{
	if(vIE() == 6)
	{
		alert("You seem to be running Internet Explorer version 6 or older.  If possible, it is advised that you upgrade to Internet Explorer version 7 so that this page displays properly.");
	}
}