How to return json string from php array

Question

I am doing something i don't understand how. written a php code in O.O.P and the value gotten from it are objects. but i want to convert this O.O.P object to JSON data to be used in by javascript. so I converted my converted my objects to array on the php end. the try to use the json_encode function on it the script just keep returning errors. so i tried using a function i scope out, it worked but the js keeps on rejecting the data. Below is the JS file

var ajax = new XMLHttpRequest();
ajax.open('GET','user.php',true);
ajax.setRequestHeader("Content-type","application/json");
ajax.onreadystatechange = function(){
  if(ajax.readyState == 4 && ajax.status ==200){
    var data = JSON.parse(ajax.responseText.trim());
    console.log(data);
    console.log(data[username]);
  }
} 
ajax.send();

it will return this error "SyntaxError: JSON.parse: bad control character in string literal at line 1 column 129 of the JSON data" without the JSON.parse it return undefind fro the data.username console log. Below is the PHP SCRIPT

    //header("Content-type: application/json");
require_once 'core/init.php';

function array2json($arr) {
    /*if (function_exists('json_encode')) {
    echo "string";
    return json_encode($arr);
    }*/

    $pars = array();
    $is_list = false;

    $keys = array_keys($arr);
    $max_length = count($arr) - 1;
    if (($keys[0] == 0) and($keys[$max_length] == $max_length)) {
        $is_list = true;
        for ($i = 0; $i < count($keys); $i++) {
            if ($i != $keys[$i]) {
                $is_list = false;
                break;
            }
        }
    }
    foreach($arr as $key => $value) {
        if (is_array($value)) {
            if ($is_list) $parts[] = array2json($value);

            else $part[] = '"'.$key.
            ':'.array2json($value);
        } else {
            $str = '';
            if (!$is_list) $str = '"'.$key.
            '"'.
            ':';
            if (is_numeric($value)) $str. = $value;
            elseif($value === false) $str. = 'false';
            elseif($value === true) $str. = 'true';
            else $str. = '"'.addslashes($value).
            '"';

            $parts[] = $str;
        }
    }
    $json = implode(',', $parts);
    if ($is_list) return '['.$json.
    ']';
    return '{'.$json.
    '}';

}


$user = new User();
$json = array();
if (!$user - > is_LOggedIn()) {
    echo "false";
} else {
    foreach($user - > data() as $key => $value) {
            $json[$key] = $value;
            //$json =json_encode($json,JSON_FORCE_OBJECT);
            //echo $json;
        }
        /*$details	= '{"'.implode('", "', array_keys($json)).'"';
        $data 		= '"'.implode('" "', $json).'"}';
        die($details.' / '.$data);*/

    $json = array2json($json);
    print $json;

}

PLEASE HELP ME OUT TO SORT THIS ERROR THANK YOU.

Answer 1

You need to set the response headers, and ensure you are not violating CORS:

    /*
     * Construct Data Structure
     */
    $response =
    [
        'value1',
        'value2'
    ];

    /*
     * Format Data
     */
    $jsonResponse = json_encode ( $response, JSON_PRETTY_PRINT );

    /*
     * Prepare Response
     */
    header('content-type: application/json; charset=UTF-8');

    /*
     * ONLY if you want/need any domain to be able to access it.
     */
    header('Access-Control-Allow-Origin: *');

    /*
     * Send Response
     */
    print_r ( $jsonResponse );

    /*
     * Return with intended destruction
     */
    die;

Answer 2

Just use the json functions json_encode and json_decode to convert arrays into json string or vice versa:

$myArray = array("value1", "value2");
echo json_encode($myArray);