// états possibles d'un XMLHttpRequest
var READY_STATE_UNINITIALIZED=0;
var READY_STATE_LOADING=1;
var READY_STATE_LOADED=2;
var READY_STATE_INTERACTIVE=3;
var READY_STATE_COMPLETE=4;

// création d'un objet XMLHttpRequest
function getXMLHttpRequest()
{
	var xhr=null;
	
	if (window.XMLHttpRequest) // Mozilla, Safari
		xhr=new XMLHttpRequest();
	else if (typeof ActiveXObject!="undefined") // Internet Explorer
		xhr=new ActiveXObject("Microsoft.XMLHTTP");
	
	return xhr;
}