JSON parse error - Javascript from PHP json_encode

I tried to solve this for eight hours, no luck, so I'm begging for help. I'm a hobbyist programmer.
Short overview: php-file reads values, creates two-dimensional array that is exported via "echo" and "json_encode". Then read by html/javascript/jquery. Then these array values should auto-populate the corresponding fields every second.

The error in Chrome Browser Console I'm getting: "Uncaught SyntaxError: Unexpected token d in JSON at position 0"

VM353:1 Uncaught SyntaxError: Unexpected token d in JSON at position 0
    at JSON.parse (<anonymous>)
    at HTMLDocument.<anonymous> ((index):16)
    at i (jquery.min.js:2)
    at Object.fireWith [as resolveWith] (jquery.min.js:2)
    at Function.ready (jquery.min.js:2)
    at HTMLDocument.K (jquery.min.js:2)

1. The following php script reads GPIO values of a Raspberry Pi into a two-dimensional array:

<?php
header('Content-Type: application/json');
$bcm05 = exec ("gpio -g read 05"); # private comment
$bcm06 = exec ("gpio -g read 06"); # private comment
$bcm16 = exec ("gpio -g read 16"); # private comment
$bcm17 = exec ("gpio -g read 17"); # private comment
$bcm22 = exec ("gpio -g read 22"); # private comment
$bcm23 = exec ("gpio -g read 23"); # private comment
$bcm24 = exec ("gpio -g read 24"); # private comment
$bcm25 = exec ("gpio -g read 25"); # private comment
$bcm26 = exec ("gpio -g read 26"); # private comment
$bcm27 = exec ("gpio -g read 27"); # private comment
$data = array('jq_bcm05' => $bcm05, 'jq_bcm06' => $bcm06, 'jq_bcm16' => $bcm16, 'jq_bcm17' => $bcm17, 'jq_bcm22' => $bcm22, 'jq_bcm23' => $bcm23, 'jq_bcm24' => $bcm24, 'jq_bcm25' => $bcm25, 'jq_bcm26' => $bcm26, 'jq_bcm27' => $bcm27);

$json = json_encode($data, true);
echo $json;
?>

2. The echo output of this script is:

{"jq_bcm05":"1","jq_bcm06":"0","jq_bcm16":"0","jq_bcm17":"0","jq_bcm22":"0","jq_bcm23":"0","jq_bcm24":"0","jq_bcm25":"0","jq_bcm26":"0","jq_bcm27":"0"}

(Note that for some reason the header is not parsed, I've tried various header changes with utf-8, at other places of the code, ... - no luck that it is parsed in the file)

3. With the following html/javascript I'm trying to import the array so that a webpage only refreshes the array vales and not the whole webpage via jquery:

<!DOCTYPE HTML>
<html>
<head>
   <title>some title</title>
   <link href="style.css" rel="stylesheet" type="text/css">
   <script src="javascript.js" type="text/javascript"></script>
   <script src="jquery.min.js"type="text/javascript"></script>

      <script>
      var php_json_array = "jquery_gpio.php";

      $(document).ready(function(){
         var arr = JSON.parse(php_json_array);
         console.log(arr.jq_bcm05);
      }); 
   </script>

4. Also another question: I do have "div id" fields in the html page that correspond exactly to the first value of the two-dimensional array. So e.g. there is a field that I would like to populate with the value "1" from the two-dimensional array. I'm too stupid to think a "for each" javascript that does this for each pair that comes from the php script. So in the end it should be like

<div id="jq_bcm05">1</>
<div id="jq_bcm06">0</>
<div id="jq_bcm17">0</>
<div id="jq_bcm22">0</>

... and so on ...

I spent a full day and I'm not getting anywhere. Your help would be deeply appreciated.
Kind regards.