Untitled

<html>
  <head>
    <title>CCTest.</title>
  </head>
  <body>
    Test.
  </body>
</html>

<?php
  $file = "data.json"

  if(empty($_GET["msg"])){ return };

  $msg = $_GET["msg"];

  $file_contents = json_decode(file_get_contents($file));

  array_push($file_contents, $msg);

  file_put_contents($file, json_encode($file_contents));
?>