mmenu wordpress plugin - bind open / close events - wordpress

Question

I am using the licenced wordpress plugin version 3.1.0.
I have the menu working, but I cannot access the mmenu API to trigger the button open / close effect I would like to use. Previously I have used the mmenu core version [not WP plugin] and triggered the class changes using this:
var $menu = $("#menu").mmenu({...})
var API = $menu.data("mmenu");
API.bind("open:finish", function () {
$("#menu-btn").addClass("is-active");
});
API.bind("close:finish", function () {
$("#menu-btn").removeClass("is-active");
});
Modifying the var API to use the plugin generated id fails with undefined, probably because the menu creation is managed in a different script.
var API = $('#mm-1').data("mmenu"); //'mm-1' - the plugin generated mmenu id
I have also tried to use jQuery direct on #menu-btn but it is not triggered unless I remove the #menu-btn from the mmenu settings. For example [not copied, just a rough example so please ignore syntax errors]:
$("#menu-btn").click(function(){console.log('click')});
all I need is to add / remove an 'is-active' class to the open menu link [id=menu-btn].

Answer 1

The mmenu adds a body class when opened, so added a mutation observer to check if the has the .mm-wrapper--opened class or not. If it does, add the 'is-active' class to the menu icon (which uses the .hamburger class) and if not, remove it.
if ($('body').hasClass('mm-wrapper--opened')){
$('.hamburger').addClass("is-active");
}
const targetNode = document.body;
const config = { childList : true, attributes: true };
const callback = function(mutationsList, observer) {
for(let mutation of mutationsList) {
if (mutation.type === 'attributes') {
if ($('body').hasClass('mm-wrapper--opened')){
setTimeout(() => { $('.hamburger').addClass("is-active"); }, 500);
}
else {
$('.hamburger').removeClass("is-active");
}
}
}
};
const observer = new MutationObserver(callback);
observer.observe(targetNode, config);