main.js

(function() {
  "use strict";

  /**
   * Easy selector helper function
   */
  const select = (el, all = false) => {
    el = el.trim()
    if (all) {
      return [...document.querySelectorAll(el)]
    } else {
      return document.querySelector(el)
    }
  }

  /**
   * Easy event listener function
   */
  const on = (type, el, listener, all = false) => {
    let selectEl = select(el, all)
    if (selectEl) {
      if (all) {
        selectEl.forEach(e => e.addEventListener(type, listener))
      } else {
        selectEl.addEventListener(type, listener)
      }
    }
  }

  /**
   * Easy on scroll event listener 
   */
  const onscroll = (el, listener) => {
    el.addEventListener('scroll', listener)
  }



  /**
   * Toggle .header-scrolled class to #header when page is scrolled
   */
  let selectHeader = select('#header')
  if (selectHeader) {
    const headerScrolled = () => {
      if (window.scrollY > 100) {
        selectHeader.classList.add('header-scrolled')
      } else {
        selectHeader.classList.remove('header-scrolled')
      }
    }
    window.addEventListener('load', headerScrolled)
    onscroll(document, headerScrolled)
  }

  /**
   * Back to top button
   */
  let backtotop = select('.back-to-top')
  if (backtotop) {
    const toggleBacktotop = () => {
      if (window.scrollY > 100) {
        backtotop.classList.add('active')
      } else {
        backtotop.classList.remove('active')
      }
    }
    window.addEventListener('load', toggleBacktotop)
    onscroll(document, toggleBacktotop)
  }



  /**
   * Preloader
   */
  let preloader = select('#preloader');
  if (preloader) {
    window.addEventListener('load', () => {
      preloader.remove()
    });
  }


  /**
   * Animation on scroll
   */
  window.addEventListener('load', () => {
    AOS.init({
      duration: 1000,
      easing: 'ease-in-out',
      once: true,
      mirror: false
    })
  });

})()