I want to send data from fetch. If I send by get method I can feth that but look at this example test.php

<?php
    print_r(json_encode($_REQUEST));

script.js

const update = {
    title: 'A blog post by Kingsley',
    body: 'Brilliant post on fetch API',
    userId: 1,
};
const options = {
    method: 'POST',
    headers: {
        'Content-Type': 'application/json',
    },
    body: JSON.stringify(update),
};

fetch('test.php', options)
    .then(data => {
        return data.json();
    })
    .then(post => {
        console.log(post);
    });

But I fetch empty array. Why? How can send and fetch data by fetch method?