Choix des paramètres à passer en GET ou POST?

var xhr_object = null; 
	 
	if(window.XMLHttpRequest) // Firefox 
	   xhr_object = new XMLHttpRequest(); 
	else if(window.ActiveXObject) // Internet Explorer 
	   xhr_object = new ActiveXObject("Microsoft.XMLHTTP"); 
	else { // XMLHttpRequest non supporté par le navigateur 
	   alert("Votre navigateur ne supporte pas les objets XMLHTTPRequest..."); 
	   return; 
	} 
	 
	var method   = f.elements["method"][0].checked ? "GET" : "POST"; 
	var filename = "strings2.php"; 
	var s1       = f.elements["string1"].value; 
	var s2       = f.elements["string2"].value; 
	var data     = null; 
	 
	if(s1 != "" && s2 != "") 
	   data = "s1="+s1+"&s2="+s2; 
	 
	if(method == "GET" && data != null) { 
	   filename += "?"+data; 
	   data      = null; 
} 
	 
	xhr_object.open(method, filename, true); 
	 
	xhr_object.onreadystatechange = function() { 
	   if(xhr_object.readyState == 4) { 
	      var tmp = xhr_object.responseText.split(":"); 
	      if(typeof(tmp[1]) != "undefined") { 
	         f.elements["string1_r"].value = tmp[1]; 
	         f.elements["string2_r"].value = tmp[2]; 
	      } 
	      alert(tmp[0]); 
	   } 
	} 
	 
	if(method == "POST") 
	   xhr_object.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); 
	 
	xhr_object.send(data);