ajax_simple

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>

  <script src="https://code.jquery.com/jquery-3.4.1.min.js"></script>
  <script>
      function clica(){
            $.post('http://localhost/simpleormteam/teste.php',{var :'teste'},function(data){
                $('#resultado').append(data);
            },'html');
      }
  </script>
</head>
<body>

  <div id="resultado"></div>

  <?php
    if(isset($_POST['var'])){
      $var = $_POST['var'];
      echo '<p style="background-color:red">' .$var.  '</p>';
      exit();
    }
  ?>

    <button onclick="clica();">Clica</button>
</body>
</html>