动画切换固定顶部导航栏

Question

Using the mdbootstrap I have navbar:

<nav class="navbar navbar-expand-lg white">

And it is positioned like this:

While scrolling I add the 'fixed-top' class to the navbar with this script:

let nav = $('.navbar').offset().top;
$(window).bind('scroll', function () {
    if  ($(window).scrollTop() >= nav)  {
        $('.navbar').addClass('fixed-top');
    } else {
        $('.navbar').removeClass('fixed-top');
    }
});

This works but: I want to animate the transition between the original and the fixed-top state. I tried with setting a transition time to .navbar{} but it does not work. Do I need to wrap the navbar into another div?

Answer 1

let nav = $('.navbar').offset().top;

Make a variable to store the offset and then update the condition for setting .fixed-top

if ($(window).scrollTop() >= nav) { 
    $('.navbar').addClass('fixed-top'); 
}

To animated:

Add a new class along with .navbar-default , say animate

.animate{
    transition: top 1s ease-in-out;
}

it will add an ease-in-out animation to the navbar.

1s is the time for animation, you can increase or decrease depending on your requirement.