var TIPO_MENU = 1;
var TIPO_CORO = 2;
var TIPO_ALBUM = 3;

var req;

function mostrarAlbum(album){
	    loadXMLDoc(album.value, TIPO_ALBUM);
}
function mostrarCoro(coro){
	    loadXMLDoc(coro.value, TIPO_CORO);
}
function mostrarMenu(menu){
	    loadXMLDoc(menu, TIPO_MENU);
}

// JavaScript Document
function loadXMLDoc(url, iTipo) 
{
    // branch for native XMLHttpRequest object
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
		if (iTipo == TIPO_MENU){
	        req.onreadystatechange = processReqChangeMenu;
		}else if (iTipo==TIPO_CORO){
	        req.onreadystatechange = processReqChangeCoro;
		}else if (iTipo==TIPO_ALBUM){
	        req.onreadystatechange = processReqChangeAlbum;
		}
        req.open("GET", url, true);
        req.send(null);
	    // branch for IE/Windows ActiveX version
    } else if (window.ActiveXObject) {
        req = new ActiveXObject("Microsoft.XMLHTTP");
        if (req) {
            if (iTipo == TIPO_MENU){
	        req.onreadystatechange = processReqChangeMenu;
		}else if (iTipo==TIPO_CORO){
	        req.onreadystatechange = processReqChangeCoro;
}else if (iTipo==TIPO_ALBUM){
	        req.onreadystatechange = processReqChangeAlbum;
}
            req.open("GET", url, true);
            req.send();
        }
    }
}
function processReqChangeMenu() 
{
    // only if req shows "complete"
    if (req.readyState == 4) {
        parseMessagesMenu();            
    }
}


function processReqChangeCoro() 
{
    // only if req shows "complete"
    if (req.readyState == 4) {
        parseMessagesCoro();
    }
}

function processReqChangeAlbum() 
{
    // only if req shows "complete"
    if (req.readyState == 4) {
        parseMessagesAlbum();
    }
}

function parseMessagesAlbum() {
        var res = document.getElementById("contenido");
 		res.innerHTML = req.responseText;
}

function parseMessagesCoro() {
        var res = document.getElementById("contenido");
 		res.innerHTML = req.responseText;
}

function parseMessagesMenu() {
	var rangeHTML = document.body.createTextRange( ) ;
	rangeHTML.pasteHTML( req.responseText );
}