$input = $modx->getOption('json', $scriptProperties);
$key = $modx->getOption('key', $scriptProperties);
$tpl = $modx->getOption('tpl', $scriptProperties, '');

$input = utf8_encode($input);
$array = json_decode($input, true);

$output = $array[$key];

if ($tpl) {
    $output = $modx->getChunk($tpl, array(
        'content' => $output
    ));
}

return $output;
Source

// @todo: write documentation and use chunks for the HTML templating

$json = $modx->getOption('json', $scriptProperties, '');
//$filterKeys = $modx->getOption('filterKeys', $scriptProperties, 'template,process_tags,field_is_exposed');
//$filterKeys = $modx->getOption('filterKeys', $scriptProperties, '"template","process_tags","field_is_exposed"');

$jsonArray = json_decode($json, true);
//$filterArray = explode(',', $filterKeys);

if (!function_exists('jsonToHTML')) {
    function jsonToHTML($array) {
        $output = '<table class="ui compact very basic table"><tbody>';

        // @todo: For some strange reason, the function won't accept filterArray to be anything other that what's below
        $filterKeys = array("templates","process_tags","field_is_exposed");

        foreach ($array as $key => $value) {
            // Exclude unwanted keys and keys with an empty value from result
            // @todo: When not set to 'true', the first item in the array will always be excluded
            if (in_array($key, $filterKeys, true) == false && $value != false) {
                $output .= "<tr class='top aligned'>";
                $output .= "<td style='width:0;'><strong>$key</strong></td>";
                $output .= "<td>";
                if (is_array($value)) {
                    $output .= jsonToHTML($value);
                } else {
                    $output .= nl2br("$value");
                }
                $output .= "</td></tr>";
            }
        }

        $output .= "</tbody></table>";

        return $output;
    }
}

return (jsonToHTML($jsonArray));
Source

/**
 * tvToJSON
 *
 * Output the properties of given TV to a JSON object.
 * The output could be used by jsonToHTML.
 *
 * Initially intended for use in the front-end library. TV settings can now be
 * loaded automatically, instead of copy/pasting the JSON from the GPM config by hand.
 *
 * Usage example:
 * [[tvToJSON? &tv=`[[+pattern_name]]`]]
 *
 */

$tvName = $modx->getOption('tv', $scriptProperties, '');

// Get the TV by name
$tv = $modx->getObject('modTemplateVar', array('name'=>$tvName));

if ($tv) {
    // Render category name for clarity
    $query = $modx->newQuery('modCategory', array(
        'id' => $tv->get('category')
    ));
    $query->select('category');
    $catName = $modx->getValue($query->prepare());

    // Render media source name for clarity
    $sourceID = $tv->get('source');
    if ($sourceID != false) {
        $query = $modx->newQuery('modMediaSource', array(
            'id' => $sourceID
        ));
        $query->select('name');
        $sourceName = $modx->getValue($query->prepare());
    }

    // Create a new object with altered elements
    // The new key names mimic the properties used by GPM
    $tvAltered = array(
        'caption' => $tv->get('caption'),
        'description' => $tv->get('description'),
        //'name' => $tv->get('name'),
        'type' => $tv->get('type'),
        'category' => $catName,
        'sortOrder' => $tv->get('rank'),
        'inputOptionValues' => str_replace('||', '<br>', $tv->get('elements')),
        'defaultValue' => $tv->get('default_text'),
        'inputProperties' => $tv->get('input_properties'),
        'outputProperties' => $tv->get('output_properties'),
        'mediaSource' => $sourceName // Not a GPM property, but good to know anyway
    );

    // Output as JSON object
    return json_encode($tvAltered);
}
Source