var page = 1;

function getXMLObject() {
    var xmlObj = null;

    try {
        var xmlObj = new XMLHttpRequest();
    }
    
    catch (error) {
        try {
            var xmlObj = new ActiveXObject("Microsoft.XMLHTTP");
        }
        catch (error) {
            window.location.reload(true);
            return true;
        }
    }
    
    return xmlObj;
}

function getTweets(dir) {
    
    if (dir < 0) {
    	if (page > 1) {
    		page--;
    	}
    } else {
    	if (page < 20) {
    		page++;
    	}
    }
    var file = '/gettweets.php?page='+page;

    var xmlObj = null;
    
    xmlObj = getXMLObject();
    
    xmlObj.onreadystatechange = function() {
        if (xmlObj.readyState == 4) {
            document.getElementById('content').innerHTML = xmlObj.responseText;
            if (page > 1) {
	            document.getElementById('link1').innerHTML="<a href='#' onclick='getTweets(-1);return false;'>&laquo; nieuwere tweets</a>";
	        } else {
	            document.getElementById('link1').innerHTML="&laquo; nieuwere tweets";
	        }
	        if (page < 20) {
	            document.getElementById('link2').innerHTML = "<a href='#' onclick='getTweets(1);return false;'>oudere tweets &raquo;</a>";
	        } else {
	            document.getElementById('link2').innerHTML="oudere tweets &raquo;";
	        }
        }
    }
    
    xmlObj.open ('GET', file, true);
    xmlObj.send ('');

    if (typeof CollectGarbage != 'undefined') { CollectGarbage(); }
}