How do I make the images fade in and out, not just appearing once, in a carousel?

I want to create a fade in/out carousel. Everything works fine but the image appears instantly instead of fading in

// JavaScript for the fade carousel
const slides = document.querySelectorAll('.carousel-slide');
let currentSlide = 0;

// Show the first slide initially
slides[currentSlide].style.display = 'block';

function nextSlide() {
  slides[currentSlide].style.display = 'none';
  currentSlide = (currentSlide + 1) % slides.length;
  slides[currentSlide].style.display = 'block';
}

// Automatically switch slides every 3 seconds
setInterval(nextSlide, 3000);

.carousel-container {
  position: relative;
  max-width: 600px;
  margin: auto;
  overflow: hidden;
}

.carousel-slide {
  display: none;
  width: 100%;
  height: 100%;
}

<div class="carousel-container">
  <img class="carousel-slide" src="https://fakeimg.pl/600x200?text=Nurses" alt="Slide 1">
  <img class="carousel-slide" src="https://fakeimg.pl/600x200?text=Barbers" alt="Slide 2">
  <img class="carousel-slide" src="https://fakeimg.pl/600x200?text=Receptionist" alt="Slide 3">
</div>

Solution

Just use opacity and css transitions. You can also listen to transitionend event if you need more control.

// JavaScript for the fade carousel
const slides = document.querySelectorAll('.carousel-slide');
let currentSlide = 0;

// Show the first slide initially
slides[currentSlide].style.opacity = '1';

function nextSlide() {
  slides[currentSlide].style.opacity = '0';
  currentSlide = (currentSlide + 1) % slides.length;
  slides[currentSlide].style.opacity = '1';
}

// Automatically switch slides every 3 seconds
setInterval(nextSlide, 3000);

.carousel-container {
  position: relative;
  max-width: 600px;
  margin: auto;
  overflow: hidden;
  
  width: 100%;
  aspect-ratio: 16/9;
}

.carousel-slide {
  width: 100%;
  height: 100%;
  transition: opacity 1s ease-out;
  opacity: 0;
  
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
}

<div class="carousel-container">
  <img class="carousel-slide" src="https://fakeimg.pl/600x400?text=Nurses" alt="Slide 1">
  <img class="carousel-slide" src="https://fakeimg.pl/600x400?text=Barbers" alt="Slide 2">
  <img class="carousel-slide" src="https://fakeimg.pl/600x400?text=Receptionist" alt="Slide 3">
</div>