Jquery - How to make disappearing header have slow transition upon disappearing

Aarroonn
May 4, 2023
208 views
0 votes
2 Answers

I have a header that disappears when the user scrolls down, and reappears when the user scrolls up. I was successful in getting the header to reappear with a slow transition, but I am unable to implement the same transition when it disappears. instead it disappears instantly which is not the intended function. I want it to have a 0.5s ease-in-out transition when disappearing like it does when it reappears. Could someone please help me create the desired effect?

 ////Header scroll effect//////

    // Hide Header on on scroll down
    var didScroll;
    var lastScrollTop = 0;
    var delta = 10;
    var navbarHeight = $('header').outerHeight();

    $(window).scroll(function(){
        didScroll = true;
    });

    setInterval(function() {
        if (didScroll) {
            hasScrolled();
            didScroll = false;
        }
    }, 250);

    function hasScrolled() {
        var st = $(this).scrollTop();
        
        // Make sure user scroll more than delta
        if(Math.abs(lastScrollTop - st) <= delta)
            return;
        
        // If user scrolled down and are past the navbar, add class .nav_up.
        if (st > lastScrollTop && st > navbarHeight){
            // Scroll Down Disappear
            $('header').removeClass('header__top').addClass('nav_up');
            $('label').removeClass('menu__btn').addClass('nav_up');
        } else {
            // Scroll Up Reappear
            if(st + $(window).height() < $(document).height()) {
                $('header').removeClass('nav_up').addClass('header__top');
                $('label').removeClass('nav_up').addClass('menu__btn');
            }
        }
        
        lastScrollTop = st;
    }

body{
  height: 30000px;
  background-color: lightblue;
  color: white;
}
.header__top {
  width: 100%;
  height: 120px;
  background-color: #000;
  position: fixed;
  top: 0px;
  z-index: 5;
  border-bottom: 0.02rem solid #000 ;
  display: flex;
  box-shadow: rgba(0, 0, 0, 0.35) 0px 5px 15px;
  transition: top 0.5s ease-in-out;
}
.nav_up { /*---scroll up effect---*/
  top: -120px;

}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<body>
<header class="header__top">
   <p>header</p>
</header>
</body>

Answers

I’ve updated a demo from w3schools. Made the transition property stay for the element using a different class. Scroll up/down detection copied from chatGPT.

const SCROLL_THRESHOLD = 10;

let lastScrollY = window.scrollY;

window.addEventListener('scroll', () => {
  const currentScrollY = window.scrollY;
  const delta = currentScrollY - lastScrollY;

  if (delta > 0 && delta >= SCROLL_THRESHOLD) {
    // The user has scrolled down by at least SCROLL_THRESHOLD pixels
    document.querySelector(".the-header").classList.add("nav_up")

  } else if (delta < 0 && -delta >= SCROLL_THRESHOLD) {
    // The user has scrolled up by at least SCROLL_THRESHOLD pixels
    document.querySelector(".the-header").classList.remove("nav_up")
  }

  lastScrollY = currentScrollY;
});

body {
  height: 3000px;
  background-color: lightblue;
  color: white;
}

.header__top {
  width: 100%;
  height: 120px;
  background-color: #000;
  position: fixed;
  top: 0px;
  z-index: 5;
  border-bottom: 0.02rem solid #000;
  display: flex;
  box-shadow: rgba(0, 0, 0, 0.35) 0px 5px 15px;
}

.the-header {
  top: 0px;
  transition: top 0.5s ease-in-out;
}

.nav_up {
  /*---scroll up effect---*/
  top: -120px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<body>
  <header class="the-header header__top">
    <p>header</p>
  </header>
</body>

As you remove the class header__top from element it also removes the transition properties. To avoid that you can add the target class and then remove the old class as a callback function:

////Header scroll effect//////

    // Hide Header on on scroll down
    var didScroll;
    var lastScrollTop = 0;
    var delta = 10;
    var navbarHeight = $('header').outerHeight();

    $(window).scroll(function(){
        didScroll = true;
    });

    setInterval(function() {
        if (didScroll) {
            hasScrolled();
            didScroll = false;
        }
    }, 250);

    function hasScrolled() {
        var st = $(this).scrollTop();
        
        // Make sure user scroll more than delta
        if(Math.abs(lastScrollTop - st) <= delta)
            return;
        
        // If user scrolled down and are past the navbar, add class .nav_up.
        if (st > lastScrollTop && st > navbarHeight){
            // Scroll Down Disappear
            $('header').addClass('nav_up',function(){$('header').removeClass('header__top')})
            $('label').removeClass('menu__btn').addClass('nav_up');
        } else {
            // Scroll Up Reappear
            if(st + $(window).height() < $(document).height()) {
                $('header').removeClass('nav_up').addClass('header__top');
                $('label').removeClass('nav_up').addClass('menu__btn');
            }
        }
        
        lastScrollTop = st;
    }

body{
  height: 30000px;
  background-color: lightblue;
  color: white;
}
.header__top {
  width: 100%;
  height: 120px;
  background-color: #000;
  position: fixed;
  top: 0px;
  z-index: 5;
  border-bottom: 0.02rem solid #000 ;
  display: flex;
  box-shadow: rgba(0, 0, 0, 0.35) 0px 5px 15px;
  transition: top 0.5s ease-in-out;
}
.nav_up { /*---scroll up effect---*/
  top: -120px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<body>
<header class="header__top">
   <p>header</p>
</header>
</body>

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Jquery – How to make disappearing header have slow transition upon disappearing

Answers