dummy-login.php

<?php
date_default_timezone_set('Asia/Tokyo');

$loginId  = isset($_POST['loginId']) ? htmlspecialchars($_POST["loginId"], ENT_QUOTES) : null;
$password = isset($_POST['password']) ? htmlspecialchars($_POST["password"], ENT_QUOTES) : null;
$memberId = "000001";

//Auth logic


//JSON dataset
$json_array = array(
    'memberId' => $memberId,
);

header("Content-Type: application/json; charset=utf-8");
echo json_encode($json_array);