Adding attributes to menus on navigation bar

We need to look at this Huge Monster – WP_Nav Walker. It looks massive but one you get the hang of it, it’s not too bad:

/** The Walker **/
class Texas_Ranger extends Walker_Nav_Menu {

    // add main/sub classes to li's and links
     function start_el( &$output, $item, $depth, $args ) {
        global $wp_query;
        $indent = ( $depth > 0 ? str_repeat( "\t", $depth ) : '' ); // code indent

        // passed classes
        $classes = empty( $item->classes ) ? array() : (array) $item->classes;

        $class_names = esc_attr( implode( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item ) ) );

        // build html
        $output .= $indent . '<li id="nav-menu-item-'. $item->ID . '" class="' . $class_names . '">';

        // link attributes
        $attributes  = ! empty( $item->attr_title ) ? ' title="'  . esc_attr( $item->attr_title ) .'"' : '';
        $attributes .= ! empty( $item->target )     ? ' target="' . esc_attr( $item->target     ) .'"' : '';
        $attributes .= ! empty( $item->xfn )        ? ' rel="'    . esc_attr( $item->xfn        ) .'"' : '';
        $attributes .= ! empty( $item->url )        ? ' href="'   . esc_attr( $item->url        ) .'"' : '';
        $attributes .= ' class="menu-link ' . ( $depth > 0 ? 'sub-menu-link' : 'main-menu-link' ) . '"';

        $item_output = sprintf( '%1$s<a%2$s>%3$s%4$s%5$s</a>%6$s',
            $args->before,
            $attributes,
            $args->link_before,
            apply_filters( 'the_title', $item->title, $item->ID ),
            $args->link_after,
            $args->after
        );

        // build html
        $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
    }
}

So you can append onto the attributes section like so:

$attributes .= ' target="_blank"';

Then you can add that to you custom nav menu via:

wp_nav_menu( array(
	'walker'	=> new Texas_Ranger()
) );