WP Term Meta Javascript

jQuery( document ).ready( function(){
    jQuery( '#thumbnail_mediathek' ).click( function( event ){
        event.preventDefault();

        if ( frame ) {
            frame.open();
            return;
        }

        // Create a new media frame
        var frame = wp.media({
            title: 'Wähle ein Kategorienbild',
            button: {
                text: 'Verwende dieses Bild'
            },
            multiple: false  // Set to true to allow multiple files to be selected
        });


        // When an image is selected in the media frame...
        frame.on( 'select', function() {
            // Get media attachment details from the frame state
            var attachment = frame.state().get('selection').first().toJSON();
            console.log( attachment );
            var txt = '<img src="' + attachment.url + '" style="max-width:100%" /><input type="hidden" name="_thumbnail_id" value="' + attachment.id + '" />';
            jQuery( '#thumbnail' ).find( 'img' ).remove();
            jQuery( txt ).insertBefore( jQuery( '#thumbnail button' ) );
        });

        // Finally, open the modal on click
        frame.open();
    });
});