wp_nav_menu change sub-menu class name?

wp_nav_menu change sub-menu class name?

from <ul class="sub-menu"> to <ul class="dropdown-menu">

You can use WordPress preg_replace filter (in your theme functions.php file) example:

function new_submenu_class($menu) {    
    $menu = preg_replace('/ class="sub-menu"/',' class="dropdown-menu" ',$menu);        
    return $menu;      
}
add_filter('wp_nav_menu','new_submenu_class');