//permet de verifier la compatibilite avec les navigateurs


function getXMLHttpRequest() 
{
	var xhr = null;
	if(window.XMLHttpRequest || window.ActiveXObject) 
	{
		if(window.ActiveXObject) 
		{
			try 
			{
				xhr = new ActiveXObject("Msxml2.XMLHTTP");
			} 
			catch(e) 
			{
				xhr = new ActiveXObject("Microsoft.XMLHTTP");
			}
		} 
		else 
		{
			xhr = new XMLHttpRequest();
		}
	}
	else 
	{
		alert("Your browser is not compatible with HttpRequest objects. Please use another one.");
		return null;
	}
	return xhr;
}