PHP json_encode {}字符

I want my json_encode to have a serialized string of:

 ['Element', 'Density', { role: 'style' }]

How do I do it?

I tried

   $data = array('Element', 'Density', "{ role: 'style' }");
   echo json_encode($data);

produces:

["Element","Density","{ role: 'style' }"]

Note the extra quotes

You nest it in another array:

$data = array('Element', 'Density', array('role' => 'style'));
                                  // ^ another nesting here
echo json_encode($data);