Change category checkbox into radio button [duplicate]

I find this function admin_js() { ?> <script type=”text/javascript”> jQuery(document).ready( function () { jQuery(‘form#post’).find(‘.categorychecklist input’).each(function() { var new_input = jQuery(‘<input type=”radio” />’), attrLen = this.attributes.length; for (i = 0; i < attrLen; i++) { if (this.attributes[i].name != ‘type’) { new_input.attr(this.attributes[i].name.toLowerCase(), this.attributes[i].value); } } jQuery(this).replaceWith(new_input); }); }); </script> <?php } add_action(‘admin_head’, ‘admin_js’);