[Vanilla JS] 무한 슬라이더 구현

💡 목표

• 외부 라이브러리를 사용하지 않고, 계속해서 반복되는 무한 슬라이더 구현
  (마지막 슬라이드에 도달하면 다시 첫번째 슬라이드로)
• 자동으로 넘어갈 것

 

📌 HTML

<div id="sliderWrap">
  <ul class="slider">
    <li>
      <div class="itemWrap"></div>
    </li>
    <li>
      <div class="itemWrap"></div>
    </li>
    <li>
      <div class="itemWrap"></div>
    </li>
  </ul>
  <div id="btn" class="directionNav">
    <button id="prev" class="btn">prev</button>
    <button id="next" class="btn">next</button>
  </div>
  <ul class="dot">
    <li class="dots on">btn01</li>
    <li class="dots">btn02</li>
    <li class="dots">btn03</li>
  </ul>
</div>

 

📌 CSS

/* reset */
li { list-style: none; }
button { border: none; }
div, ul, li, button { margin: 0; padding: 0; }

#sliderWrap { position: relative; width: 300px; height: 200px; overflow: hidden; }

/* slide item */
#sliderWrap .slider { position: absolute; top: 0; left: 0; height: 100%;}
#sliderWrap .slider li { float: left; position: relative; top: 0; left: 0; height: 100%; }
#sliderWrap .slider li .itemWrap { width: 100%; height: 100%; text-align: center; }

/* item background color */
#sliderWrap .slider li:nth-child(1) .itemWrap { background-color: #ff8181; }
#sliderWrap .slider li:nth-child(2) .itemWrap { background-color: #fff281; }
#sliderWrap .slider li:nth-child(3) .itemWrap { background-color: #81d1ff; }

/* button */
#sliderWrap .directionNav { position: relative; width: 100%; height: 100%; }
#sliderWrap .directionNav button { position: absolute; top: 50%; transform: translateY(-50%); width: 20px; height: 20px; font-size: 0; background: none; cursor: pointer; }
#sliderWrap .directionNav button::after { display: block; content: ""; width: 100%; height: 100%; border-right: 3px solid #000; border-top: 3px solid #000; transform: rotate(45deg); opacity: 0.6; }
#sliderWrap .directionNav button#prev { left: 20px; }
#sliderWrap .directionNav button#prev::after { transform: rotate(-135deg); }
#sliderWrap .directionNav button#next { right: 20px; } 

/* pagination */
.dot { position: absolute; bottom: 10px; left: 50%; transform: translateX(-50%); }
.dot li { float: left; width: 10px; height: 10px; margin: 0 4px; border-radius: 50px; background: #000; opacity: 0.3; text-indent: -9999px; cursor: pointer; }
.dot li.on { opacity: 1; }

 

📌 JavaScript

function initializeSlider() {
  const slideWrapper = document.getElementById('sliderWrap');
  const slider = document.querySelector('#sliderWrap .slider');
  const slides = document.querySelectorAll('#sliderWrap .slider li');
  const sliderWidth = slideWrapper.clientWidth;
  const totalSlides = slides.length;
  
  let slideIndex = 0;
  let autoSlider;

  // Set slide widths
  slides.forEach(function (element) {
    element.style.width = sliderWidth + 'px';
  });

  slider.style.width = sliderWidth * totalSlides + 'px';

  // Next, Prev, Pagination
  const nextBtn = document.getElementById('next');
  const prevBtn = document.getElementById('prev');
  const dot = document.querySelector('.dot');
  const allBtn = document.getElementById('btn');

  function plusSlides(n) {
    showSlides(slideIndex + n);
  }

  function showSlides(n) {
    slideIndex = (n + totalSlides) % totalSlides;
    slider.style.left = -(sliderWidth * slideIndex) + 'px';
    pagination();
  }

  function currentSlides(n) {
    showSlides(n);
  }

  function pagination() {
    const dots = document.querySelectorAll('.dot li');
    dots.forEach(function (element) {
      element.classList.remove('on');
    });
    dots[slideIndex].classList.add('on');
  }

  // Handle dot clicks
  dot.addEventListener('click', function (event) {
    if (event.target.tagName === 'LI') {
      showSlides(Array.from(event.target.parentNode.children).indexOf(event.target));
    }
  });

  // Handle button clicks
  nextBtn.addEventListener('click', function () {
    plusSlides(1);
  });

  prevBtn.addEventListener('click', function () {
    plusSlides(-1);
  });

  // Handle hover
  const hoverElements = [allBtn, dot];

  hoverElements.forEach(function (element) {
    element.addEventListener('mouseover', function () {
      this.classList.add('active');
      clearInterval(autoSlider);
    });

    element.addEventListener('mouseleave', function () {
      this.classList.remove('active');
      startAutoSlider();
    });
  });

  // Auto slider
  function startAutoSlider() {
    autoSlider = setInterval(function () {
      plusSlides(1);
    }, 3000);
  }

  // Initialize auto slider
  startAutoSlider();
}

// 호출하여 슬라이더 초기화
initializeSlider();

 

💛 결과물

 

 

 

 

Html 아이콘 제작자: Freepik - Flaticon
Css 아이콘 제작자: Freepik - Flaticon
자바 스크립트 아이콘 제작자: Rmpp - Flaticon

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