mdbootstrap/js/modules/treeview.js

Material Design for Bootstrap (MDB) is a powerful Material Design UI KIT for most popular HTML, CSS, and JS framework - Bootstrap.

"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");
  });
}