<script>
     var url = "https://dir.by/developer/myapi/login.php";

     var params = "login=evgen&password=12345";

     xmlHttpReq = new XMLHttpRequest();
     xmlHttpReq.open('POST', url, true);
     xmlHttpReq.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
     xmlHttpReq.onreadystatechange = function()
     {
          if (xmlHttpReq.readyState == 4 && xmlHttpReq.status == 200) // success
          {
               alert(xmlHttpReq.responseText);
          }
     }
     xmlHttpReq.send(params);
</script>

<?php

header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: GET, POST, OPTIONS, PUT, DELETE');
header('Access-Control-Allow-Headers: Content-Type, Authorization, X-Requested-With');

header('Content-Type: application/json');

$response = array();
$response['success'] = false;

if ($_REQUEST['login']=='evgen' && $_REQUEST['password']=='12345')
{
     $response['success'] = true;
     $response['token'] = "123123dasa213ws212";
}

echo json_encode($response);

?>

<script>
     var url = "https://dir.by/developer/myapi/login.php";

     var params = "login=evgen&password=12345";

     xmlHttpReq = new XMLHttpRequest();
     xmlHttpReq.open('POST', url, true);
     xmlHttpReq.setRequestHeader('Content-Type', 'application/json' 'application/x-www-form-urlencoded');
     xmlHttpReq.onreadystatechange = function()
     {
          if (xmlHttpReq.readyState == 4 && xmlHttpReq.status == 200) // success
          {
               alert(xmlHttpReq.responseText);
          }
     }
     xmlHttpReq.send(params);
</script>