function getXhr()
{
	var xhr = null;
	 
	if(window.XMLHttpRequest) xhr = new XMLHttpRequest(); //FF and Co
	
	else if(window.ActiveXObject) //IE
	{ 
		try 
		{
	        xhr = new ActiveXObject("Msxml2.XMLHTTP");
	    } catch (e) {
	        xhr = new ActiveXObject("Microsoft.XMLHTTP");
	    }
	    
	} else {
		alert("Votre navigateur ne supporte pas les objets XMLHTTPRequest..."); 
		xhr = false; 
	}
	
	return xhr;
}