script.js

window.addEventListener('scroll', onScroll)

onScroll()

function onScroll() {
  showNavOnScroll()
  showBackToTopOnScroll()

  activateMenuAtCurrentSection(home)
  activateMenuAtCurrentSection(services)
  activateMenuAtCurrentSection(about)
  activateMenuAtCurrentSection(contact)
};

function activateMenuAtCurrentSection(section) {
  const targetLine = scrollY + innerHeight / 2

  //verificar se a seção passou da linha
  const sectionTop = section.offsetTop
  const sectionHeight = section.offsetHeight

  const sectionTopReachOrPassedTargetLine = targetLine >= sectionTop

  //verificar se a base esta abaixo da linha alvo
  const sectionEndsAt = sectionTop + sectionHeight

  const sectionEndPassedTargetLine = sectionEndsAt <= targetLine

  // Limites da seção
  const sectionBoundaries = sectionTopReachOrPassedTargetLine && !sectionEndPassedTargetLine

  const sectionId = section.getAttribute('id')
  const menuElement = document.querySelector(`.menu a[href*=${sectionId}]`)

  menuElement.classList.remove('active')
  if (sectionBoundaries) {
    menuElement.classList.add('active')
  }

}

function showNavOnScroll() {
  const navigation = document.querySelector("#navigation");

  if (scrollY > 0) {
    navigation.classList.add("scroll");
  } else {
    navigation.classList.remove("scroll");
  }
};

function showBackToTopOnScroll () {
  const backToTopButton = document.querySelector("#backToTopButton");

  if (scrollY > 800) {
    backToTopButton.classList.add("show");
  } else {
    backToTopButton.classList.remove("show");
  }

  /* if (scrollY > 4440) {
    backToTopButton.classList.add("change");
  } else {
    backToTopButton.classList.remove("change");
  } */
};

function openMenu() {
  document.body.classList.add("menu-expanded");
};

function closeMenu() {
  document.body.classList.remove("menu-expanded");
};

ScrollReveal({
  origin: "top",
  distance: "50px",
  durstion: 700,
}).reveal(
  "#home, #home img, #home .datas, #services, #services header, #services .card, #about header, #about .content"
);