Custom blocks give jquery error, ajax filtering not working

class td_block_27 extends td_block {

function render($atts, $content = null) {
parent::render($atts); // sets the live atts, $this->atts, $this->block_uid, $this->td_query (it runs the query)

$buffy = ''; //output buffer

//get the js for this block
$buffy .= $this->get_block_js();

$buffy .= '<div class="' . $this->get_block_classes() . '">';

//get the block title
$buffy .= $this->get_block_title();

//get the sub category filter for this block
//$buffy .= $this->get_pull_down_filter();

$buffy .= '<div id=' . $this->block_uid . ' class="td_block_inner">';
$buffy .= $this->inner($this->td_query->posts); //inner content of the block
$buffy .= '</div>';

//get the ajax pagination for this block
$buffy .= $this->get_block_pagination();
$buffy .= '</div> <!-- ./block -->';
return $buffy;
}

function inner($posts, $td_column_number = '') {

$buffy = '';

$td_block_layout = new td_block_layout();
if (empty($td_column_number)) {
$td_column_number = td_global::vc_get_column_number(); // get the column width of the block from the page builder API
}
$td_post_count = 0; // the number of posts rendered
$td_current_column = 1; //the current columng
$td_column_number = 1;
if (!empty($posts)) {
foreach ($posts as $post) {
$td_module_27 = new td_module_27($post);

switch ($td_column_number) {

case '1': //one column layout
$buffy .= $td_block_layout->open12(); //added in 010 theme - span 12 doesn't use rows
$buffy .= $td_module_27->render($post);
$buffy .= $td_block_layout->close12();
break;

case '2': //two column layout
$buffy .= $td_block_layout->open_row();

$buffy .= $td_block_layout->open6();
$buffy .= $td_module_27->render($post);
$buffy .= $td_block_layout->close6();

if ($td_current_column == 2) {
$buffy .= $td_block_layout->close_row();
}

break;

case '3': //three column layout
$buffy .= $td_block_layout->open_row();

$buffy .= $td_block_layout->open4();
$buffy .= $td_module_27->render($post);
$buffy .= $td_block_layout->close4();

if ($td_current_column == 3) {
$buffy .= $td_block_layout->close_row();
}

break;
}

//current column
if ($td_current_column == $td_column_number) {
$td_current_column = 1;
} else {
$td_current_column++;
}

$td_post_count++;
}
}
$buffy .= $td_block_layout->close_all_tags();
return $buffy;
}

/**
* renders the filter of the block
* @return string
*/
function get_pull_down_filter() {
$buffy = '';

$td_pull_down_items = $this->get_td_pull_down_items();
if (empty($td_pull_down_items)) {
return '';
}

//generate unique id for this pull down filter control
$pull_down_wrapper_id = "td_pulldown_" . $this->get_block_uid();

// wrapper
$buffy .= '<div class="td-pulldown-syle-default td-subcat-filter" id="' . $pull_down_wrapper_id . '">';

// subcategory list
$buffy .= '<ul class="td-subcat-list" id="' . $pull_down_wrapper_id . '_list">';
foreach ($td_pull_down_items as $item) {
$buffy .= '<li class="td-subcat-item">get_block_uid() . '" href="#">' . $item['name'] . '';
}
$buffy .= '';

// subcategory dropdown list
$buffy .= '<div class="td-subcat-dropdown">';
$buffy .= '<div class="td-subcat-more" aria-haspopup="true"><span>' . __td('More', TD_THEME_NAME) . '</span><i class="td-icon-read-down"></i></div>';

// the dropdown list
$buffy .= '<ul class="td-pulldown-filter-list">';

$buffy .= '';

$buffy .= '</div>';
$buffy .= '</div>';

return $buffy;
}