/*******************************************************************************
* Author: Justin Barlow - www.netlobo.com
* Project Netlobo Ajax v1.1
* the ajaxUpdate( ) function tries to make AJAX operations easier by performing
* many common AJAX related operations in one place. The function will request
* the data from the given "url" and inject it into the html element with the
* given "elemid" using the element's innerHTML method. This function is most
* useful when the requested "url" returns html formatted text or plain text. The
* "url" does not have to return XML.
* 
* The "options" parameter is an anonymous object which includes the following
* available options:
* 
* params:     Parameters for the requested url in the format p1=1&p2=0&p3=2
* meth:       The request method. Can be "get" or "post". Default is "get".
* async:      Toggles asynchronous mode. Default is true.
* startfunc:  A function or list of functions to be called before the AJAX
*             request is made. A list of functions must be separated by the
*             semi-colon like this: "showLoad(); animateText(); hideDiv('bob')".
*             You can pass parameters into the functions.
* endfunc:    A function or list of functions to be called after a successful
*             AJAX request. Uses the same format as "startfunc".
* errorfunc:  A function or list of functions to be called when the AJAX request
*             is unsuccessful. Uses the same format as "startfunc".
* noauthfunc: A function or list of functions to be called when the AJAX request
*             is not authenticated (http status code 403 is encountered). Uses
*             the same format as "startfunc".
* 
* Returns true on success and false on failure.
* 
* Example Usage:
* 
	ajaxUpdate( "rightdiv", "getData.jsp", {
		params:"id=12&AJAX=true",
		meth:"post",
		async:true,
		startfunc:"elemOn('loading')",
		endfunc:"elemOff('loading'); elemOn('rightdiv')",
		errorfunc:"ajaxError()",
		noauthfunc:"ajaxNoAuth()" }
	);
* 
* 
* 
* If need to include a start or end function call with parameters then split the request
* into two parts and use the gofunc / gotarget and stopfunc / stop target params like so:
* ie. onclick="comet('sometarget','someurl', {startfunc:"openLayer('targetlayer')"}"
* the above won't work because of the nesting ""s.  So instead do this:
* onclick="comet('sometarget','someurl', {gofunc:'openLayer', gotarget:'targetlayer'}"
*******************************************************************************/
function comet( elemid, url, options )
{
	var params = options.params || "";
	var meth = options.meth || "get";
	var async = options.async;
	if( async == null )
		async = true;
	var startfunc = options.startfunc || "";
	var endfunc = options.endfunc || "";
	var gofunc = options.gofunc || "";
	var gotarget = options.gotarget || "";
	var stopfunc = options.stopfunc || "";
	var stoptarget = options.stoptarget || "";
	var errorfunc = options.errorfunc || "";
	var noauthfunc = options.noauthfunc || "";
	var req = false;
	if( window.XMLHttpRequest )
		req = new XMLHttpRequest();
	else if( window.ActiveXObject )
		req = new ActiveXObject( "Microsoft.XMLHTTP" );
	else
	{
		alert(  "Your browser cannot perform the requested action. "+
				"Either your security settings are too high or your "+
				"browser is outdated. Try the newest version of "+
				"Internet Explorer or Mozilla Firefox." );
		return false;
	}
	
	if(gofunc != "")
		startfunc = gofunc+"('"+gotarget+"')";

	if(stopfunc != "")
		endfunc = stopfunc+"('"+stoptarget+"')";
	
	if( startfunc != "" )
		eval( startfunc );
	
	req.onreadystatechange =
		function()
		{
			if ( req.readyState == 4 ) 
			{
				if ( req.status == 200 )
				{
					if( elemid != '' )
						document.getElementById(elemid).innerHTML = req.responseText;
					if( endfunc != "" )
						eval( endfunc );
					return true;
				}
				else
				{
					if( req.status == 403 && noauthfunc != "" )
						eval( noauthfunc );
					else
					{
						if( endfunc != "" )
							eval( endfunc );
						if( errorfunc != "" )
							eval( errorfunc );
					}
					return false;
				}
			}
		};
	if( meth == "get" )
	{
		req.open( meth, url+( params != "" ? "?"+params : "" ), async );
		req.send(null);
	}
	else
	{
		req.open( meth, url, async );
		req.setRequestHeader( "Content-Type", "application/x-www-form-urlencoded" );
		req.send( params );
	}
}