How to set a block of image carousels in javascript css-Front-end Q&A-php.cn

With the continuous development of the Internet, image carousels have become an important part of website design and development. In this article, we’ll cover how to create an image carousel using JavaScript and CSS.

First, we need an HTML template, and some CSS to set the appearance of the carousel.

<code class="html"><div class="slider-container">
   <div class="slider-wrapper">
      <div class="slider-slide">
         <img src="image1.jpg">
      </div>
      <div class="slider-slide">
         <img src="image2.jpg">
      </div>
      <div class="slider-slide">
         <img src="image3.jpg">
      </div>
      <div class="slider-slide">
         <img src="image4.jpg">
      </div>
   </div>
   <button class="slider-prev">&#10094;</button>
   <button class="slider-next">&#10095;</button>
</div></code>

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In this HTML template, we use a <div> element that contains an image as a separate slideshow. We will place these slides in a parent element that contains all the slides. At the bottom, we also have two "prev" and "next" buttons that control the slideshow.

Next, we will use CSS to set up the UI of this slideshow.

<code class="css">.slider-container {
   position: relative;
   width: 100%;
   height: 500px;
   overflow: hidden;
}

.slider-wrapper {
   display: flex;
   position: absolute;
   top: 0;
   left: 0;
   width: 100%;
   height: 100%;
   transition: transform 0.5s ease;
}

.slider-slide {
   flex: 1;
   display: flex;
   align-items: center;
   justify-content: center;
}

.slider-slide img {
   max-width: 100%;
   max-height: 100%;
   object-fit: contain;
}

.slider-prev,
.slider-next {
   position: absolute;
   top: 50%;
   transform: translateY(-50%);
   width: 50px;
   height: 50px;
   border-radius: 50%;
   background: rgba(0, 0, 0, 0.5);
   color: white;
   font-size: 20px;
   border: none;
   cursor: pointer;
   opacity: 0.5;
   transition: opacity 0.2s ease;
}

.slider-next {
   right: 20px;
}

.slider-prev {
   left: 20px;
}

.slider-prev:hover,
.slider-next:hover {
   opacity: 0.8;
}</code>

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In this CSS, we first set the position and size of the <div> element that contains the carousel. Then we set the position and size of each slide in the slider-wrapper. The trick here is to make each slide a flex container so that they can center the image.

Finally, we set the position, style, and functionality of our "prev" and "next" buttons.

Now that we have the look and UI set up for our carousel slideshow, we need to add some logic using JavaScript.

<code class="javascript">var sliderWrapper = document.querySelector('.slider-wrapper');
var slides = document.querySelectorAll('.slider-slide');
var prevBtn = document.querySelector('.slider-prev');
var nextBtn = document.querySelector('.slider-next');
var slideIndex = 0;

function moveSlides() {
   sliderWrapper.style.transform = "translateX(" + (-slides[slideIndex].offsetLeft) + "px)";
}

nextBtn.addEventListener('click', function() {
   if (slideIndex >= slides.length - 1) {
      slideIndex = 0;
   } else {
      slideIndex++;
   }
   moveSlides();
});

prevBtn.addEventListener('click', function() {
   if (slideIndex <= 0) {
      slideIndex = slides.length - 1;
   } else {
      slideIndex--;
   }
   moveSlides();
});</code>

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This code selects our slide and button elements and adds a click action so that the slide can move forward or backward. Each button click is handled by its own event listener. In the click event we first check if the slide has reached the last one, if so we reset the slide index to zero. Otherwise, we just move one slide forward or backward and call the moveSlides() function to switch between slide groups.

Finally, we need to add an auto-rotate feature, which will automatically rotate the slides without user intervention.

<code class="javascript">var sliderInterval = setInterval(function() {
   if (slideIndex >= slides.length - 1) {
      slideIndex = 0;
   } else {
      slideIndex++;
   }
   moveSlides();
}, 5000);

sliderWrapper.addEventListener('mouseenter', function() {
   clearInterval(sliderInterval);
});

sliderWrapper.addEventListener('mouseleave', function() {
   sliderInterval = setInterval(function() {
      if (slideIndex >= slides.length - 1) {
         slideIndex = 0;
      } else {
         slideIndex++;
      }
      moveSlides();
   }, 5000);
});</code>

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Here, we use a setInterval function that automatically moves the slide forward at intervals of 5 seconds. We also added mouseover and mouseout event listeners to stop and run the automatic carousel when the user hovers over the slide.

Okay, we have completed the design and development of our image carousel. The final code is as follows:

<code class="html"><div class="slider-container">
   <div class="slider-wrapper">
      <div class="slider-slide">
         <img src="image1.jpg">
      </div>
      <div class="slider-slide">
         <img src="image2.jpg">
      </div>
      <div class="slider-slide">
         <img src="image3.jpg">
      </div>
      <div class="slider-slide">
         <img src="image4.jpg">
      </div>
   </div>
   <button class="slider-prev">&#10094;</button>
   <button class="slider-next">&#10095;</button>
</div>

<style>
    .slider-container {
       position: relative;
       width: 100%;
       height: 500px;
       overflow: hidden;
    }
    
    .slider-wrapper {
       display: flex;
       position: absolute;
       top: 0;
       left: 0;
       width: 100%;
       height: 100%;
       transition: transform 0.5s ease;
    }
    
    .slider-slide {
       flex: 1;
       display: flex;
       align-items: center;
       justify-content: center;
    }
    
    .slider-slide img {
       max-width: 100%;
       max-height: 100%;
       object-fit: contain;
    }
    
    .slider-prev,
    .slider-next {
       position: absolute;
       top: 50%;
       transform: translateY(-50%);
       width: 50px;
       height: 50px;
       border-radius: 50%;
       background: rgba(0, 0, 0, 0.5);
       color: white;
       font-size: 20px;
       border: none;
       cursor: pointer;
       opacity: 0.5;
       transition: opacity 0.2s ease;
    }
    
    .slider-next {
       right: 20px;
    }
    
    .slider-prev {
       left: 20px;
    }
    
    .slider-prev:hover,
    .slider-next:hover {
       opacity: 0.8;
    }  
</style>

<script>
    var sliderWrapper = document.querySelector('.slider-wrapper');
    var slides = document.querySelectorAll('.slider-slide');
    var prevBtn = document.querySelector('.slider-prev');
    var nextBtn = document.querySelector('.slider-next');
    var slideIndex = 0;

    function moveSlides() {
       sliderWrapper.style.transform = "translateX(" + (-slides[slideIndex].offsetLeft) + "px)";
    }

    nextBtn.addEventListener('click', function() {
       if (slideIndex >= slides.length - 1) {
          slideIndex = 0;
       } else {
          slideIndex++;
       }
       moveSlides();
    });

    prevBtn.addEventListener('click', function() {
       if (slideIndex <= 0) {
          slideIndex = slides.length - 1;
       } else {
          slideIndex--;
       }
       moveSlides();
    });

    var sliderInterval = setInterval(function() {
       if (slideIndex >= slides.length - 1) {
          slideIndex = 0;
       } else {
          slideIndex++;
       }
       moveSlides();
    }, 5000);

    sliderWrapper.addEventListener('mouseenter', function() {
       clearInterval(sliderInterval);
    });

    sliderWrapper.addEventListener('mouseleave', function() {
       sliderInterval = setInterval(function() {
          if (slideIndex >= slides.length - 1) {
             slideIndex = 0;
          } else {
             slideIndex++;
          }
          moveSlides();
       }, 5000);
    });
</script></code>

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Now if you copy this code into your local file and replace the slideshow image and path with your own content, you will get a nice JavaScript and CSS image carousel.

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