php - json_encode not working with a html string as value

Question

I am debugging this ajax for quite a time now. I have this on my jQUery file:

$("#typeForm").ajaxForm({
    success : function(html){
        alert(html);
}).submit();

This calls service.php, and within it I have this:

$data = array('upload_data' => $this->upload->data());
$str = "<div style='position:relative'><img src='/assets/ui/success.png' /><span style='position:relative;top:-15px;'>Nachricht empfangen!</span></div>";
echo json_encode(array('file_name' => $data['upload_data']['file_name'], 'prompt' => $str));

This won't work. But by replacing $str to $str = "HELLO WORLD"; the jQuery alerts what should I expected. What seems to be the problem?

EDIT:

Here is a screenie of the output:

It does alerts, but if I modify my jQuery into this:

$("#typeForm").ajaxForm({
    success : function(html){
        var obj = $.parseJSON(html);
        alert(obj);
}).submit();

Then it does nothing at all, even alerting.

I did a var_dump on the json_encode and here is the dump, it looks like a malformed JSON:

string(214) "{"file_name":"cde595988d386529909ce5a8fe3a6d6f.png","prompt":"<div style="position:relative;"><img src="/assets/ui/success.png" =""><span style="position:relative;top:-15px;">Nachricht empfangen!&lt;/span&gt;&lt;/div&gt;"}"
</span></div>

Here is the full content of service.php

class Service extends CI_Controller
{
    public function __construct()
    {
        parent::__construct();
    }
    public function index()
    {
        $filename = 'uploadfile';

        $config['upload_path'] = './uploads/temp';
        $config['allowed_types'] = 'jpg|png|gif|doc|docx|pdf|ppt|pptx|xls|xlsx|bmp';
        $config['max_size'] = '3072';
        $config['encrypt_name'] = TRUE;
        $config['remove_spaces'] = TRUE;

        $this->load->library('upload', $config);

        if (!$this->upload->do_upload($filename))
        {
            $error = array('error' => $this->upload->display_errors());
                    echo json_encode(array('error' => $error['error']));
        }
        else
        {
            $data = array('upload_data' => $this->upload->data());
            $file_name = $data['upload_data']['file_name'];
            //print_r($data);
            //echo json_encode(array('test' => "Hello World"));
            $str = "<div style='position:relative;'><img src='/assets/ui/success.png' /><span style='position:relative;top:-15px;'>Nachricht empfangen!</span></div>";
            $str2 = json_encode(array("file_name" => $file_name, "prompt" => $str));
            //var_dump($str2);
            exit(json_encode(array('file_name' => $data['upload_data']['file_name'], 'prompt' => $str)));
        }
    }
}

Answer 1

I was having same problem with json_encode today. But after testing a lot I found the correct solution:

In PHP to encode the array or string:

json_encode($array, JSON_HEX_QUOT | JSON_HEX_TAG);

In JS to decode the same:

var d = $.parseJSON(content);