PHP POST JSON JavaScript Fetch Example 2

post.js

const options = {
  method: 'post',
  headers: {
    'Content-type': 'application/x-www-form-urlencoded; charset=UTF-8'
  },
  body: 'json={data: "data"}'
}

let url = "post.php";

fetch(url, options)
    .then(response => {
      return response.text(); // returns text that can used as html
      //return response.json();  // returns json object
    })
    .then(html => {
      document.querySelector("#html_element").innerHTML = html;
    })
    .then(() => {
     // do something else;
    })
    .catch(function(err) {
      console.log("Failed to fetch page: ", err);
    });
    .catch(err => {
    console.error('Request failed', err)
})

post.php

<?php

$data = json_decode($_POST['json']);

?>