mdbootstrap/js/modules/treeview.js

<p align="center"> <a href="https://mdbootstrap.com/docs/jquery/getting-started/download/"> <img src="https://mdbootstrap.com/img/Marketing/general/logo/medium/mdb-r.png"> </a> </p>

"use strict";

var toggler = document.getElementsByClassName("rotate");
var i;

for (i = 0; i < toggler.length; i++) {
  toggler[i].addEventListener("click", function () {
    this.parentElement.querySelector(".nested").classList.toggle("active");
    this.classList.toggle("down");
  });
}