Bootstrap Avoid navbar-toggle button to close opened sub menus on mobile

I have a code based on Bootstrap 3.3.7
There are different menu items and sub menus on my menu, I want to have all sub menu items to be open on mobile, Means no need to click on any menu items to display it's sub menus, So I wrote a JS code to open all sub menus on mobile:

function opensubmenus() {
  if ($(window).width() < 768) {
    $("#top-navbar-collapse li").addClass('open');
  } else {
    $("#top-navbar-collapse li").removeClass('open');
  }
}

$(window).resize(opensubmenus);
opensubmenus();

But the problem is when I click on navbar-toggle button, It closes all sub menus, But I need to keep them open on mobile devices all the time

from Bootstrap Avoid navbar-toggle button to close opened sub menus on mobile