To enable creating a menu from a Bootstrap navbar collapse, add "bootstrap4" to the wrappers option.

      "DOMContentLoaded", () => {
         new Mmenu( "#my-menu", {
            wrappers: ["bootstrap4"]

What it does

Using the "bootstrap" wrapper will refactor the HTML for a Bootstrap navbar collapse to work with mmenu. It can refactor lists (.navbar-nav), text, dropdowns (.dropdown-menu and forms (.form-inline).

It also sets the classNames.selected configuration option to the default classname used by Bootstrap.

Next wrapper: