Drupal 6’s drupal_json method encodes ampersands incorrectly for JQuery 1.5, causing the rather cryptic error:

Uncaught Syntax error, unrecognized expression: ...

(If you’re lucky.)

The way to fix this is to borrow the JSON-handling code from Drupal 7. Here’s something you might be able to use:

function yourmodule_json_encode($var) {
  return str_replace(array('<', '>', '&'), array('\u003c', '\u003e', '\u0026'), $var);
}

// Fix Drupal JSON problems from http://witti.ws/blog/2011/03/14/jquery-15-json-parse-error
function yourmodule_json($var) {
  drupal_set_header('Content-Type: text/javascript; charset=utf-8');
  if (isset($var)) {
    echo yourmodule_json_encode(json_encode($var));
  }
}

Use yourmodule_json instead of drupal_json wherever applicable.

Hat tip to Greg Payne (Witti) for pointing me in the right direction!

2011-08-04 Thu 14:01