“connexion refusée xmlhttprequest” Réponses codées

connexion refusée xmlhttprequest

var xhttp= new XMLHttpRequest();
xhttp.onreadystatechange = function() {
console.log(xhttp);

xhttp.onerror = function(e){
    alert("Unknown Error Occured. Server response not received.");
};

xhttp.open("POST", "http://localhost:8080/data", true);
xhttp.send();