function verifierLogin(quel)
{
	   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;
	   }
	   
	   xhr_object.open("POST", "verifier_username.php", true);
		
	   xhr_object.onreadystatechange = function()
	   {
		  if(xhr_object.readyState == 4)
			 eval(xhr_object.responseText);
	   }
	   
	   xhr_object.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	   var data = "login="+escape(quel);
	   xhr_object.send(data);
}

function verifierLoginPourModifInfosUsager(login,id)
{
	   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;
	   }
	   
	   xhr_object.open("POST", "verifier_username.php", true);
		
	   xhr_object.onreadystatechange = function()
	   {
		  if(xhr_object.readyState == 4)
			 eval(xhr_object.responseText);
	   }
	   
	   xhr_object.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	   var data = "login="+escape(login)+"&id="+escape(id);
	   xhr_object.send(data);
}
/*
function verifierCourriel(quel)
{
	   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;
	   }
	   
	   xhr_object.open("POST", "verifier_courriel.php", true);
		
	   xhr_object.onreadystatechange = function()
	   {
		  if(xhr_object.readyState == 4)
			 eval(xhr_object.responseText);
	   }
	   
	   xhr_object.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	   var data = "login="+escape(quel);
	   xhr_object.send(data);
}*/