[RESOLVED] Change an item status from HTML webpage - Openhab 3.0

Setup, Configuration and Use Beginners
1

Dear all,
I would like to change the state of an item from a personal http/javascript webpage.
I have found this function on the forum :

function sendCommand(item, data) {
  var urlBase = "http://xx-xx-server/rest/items/"
  var url=urlBase + item;
  var xhr = new XMLHttpRequest();
  xhr.open("POST", url);
  xhr.setRequestHeader("Content-Type", "text/plain");
  xhr.setRequestHeader("Accept", "application/json");

  xhr.onreadystatechange = function () {
     if (xhr.readyState === 4) {
      console.log(xhr.status);
      console.log(xhr.responseText);
     };
  }
  xhr.send(data); 
}

do you know the correction of this function to integrate the login / password of openhab 3.0 ?

EDIT :
I try to add :
xhr.setRequestHeader(“Authorization”, "Basic " + btoa(“admin:xxx”));
but finaly I use :

function test() {

  fetch('http://xx-xx-server/rest/items/switchNeosmart', {

    method: 'POST',

    headers: {

        'accept': '*/*',

        'Content-Type': 'text/plain',

        'Authorization': 'Basic' + btoa("admin:xxxxx")

    },

    body: 'ON'

});

i have found a solution for CORS error message :
conf/services/runtime.cfg : org.openhab.cors:enable=true