function getXhr(){
	var xhr = null; 
	if(window.XMLHttpRequest)  xhr = new XMLHttpRequest(); else if(window.ActiveXObject) { 
	   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;
}
function graph() {
  var id=document.getElementById("selprod").value;
	var xhr; var send; var reponse; xhr = getXhr();
	xhr.onreadystatechange = function() {		
        if(xhr.readyState == 4 && xhr.status == 200) { reponse = xhr.responseText;
            if(reponse != '') { 
              document.getElementById("graphcours").innerHTML=xhr.responseText;
            } }
    }
    send = "id="+id;
    xhr.open("POST","graph1.php",true);
    xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded'); xhr.send(send);
}
function graph2() {
  var id=document.getElementById("selprod").value;
	var xhr; var send; var reponse; xhr = getXhr();
	xhr.onreadystatechange = function() {		
        if(xhr.readyState == 4 && xhr.status == 200) { reponse = xhr.responseText;
            if(reponse != '') { 
              document.getElementById("graphmarches").innerHTML=xhr.responseText;
            } }
    }
    send = "id="+id;
    xhr.open("POST","graph2.php",true);
    xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded'); xhr.send(send);
}
function graph3() {
  var id=document.getElementById("selprod").value;
	var xhr; var send; var reponse; xhr = getXhr();
	xhr.onreadystatechange = function() {		
        if(xhr.readyState == 4 && xhr.status == 200) { reponse = xhr.responseText;
            if(reponse != '') { 
              document.getElementById("graphprod").innerHTML=xhr.responseText;
            } }
    }
    send = "id="+id;
    xhr.open("POST","graph3.php",true);
    xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded'); xhr.send(send);
}
function graph4() {
  var id=document.getElementById("selprod").value;
	var xhr; var send; var reponse; xhr = getXhr();
	xhr.onreadystatechange = function() {		
        if(xhr.readyState == 4 && xhr.status == 200) { reponse = xhr.responseText;
            if(reponse != '') { 
              document.getElementById("graphtrans").innerHTML=xhr.responseText;
            } }
    }
    send = "id="+id;
    xhr.open("POST","graph4.php",true);
    xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded'); xhr.send(send);
}