Простой слайдер

перепроверить

class Slider {
  constructor(selector) {
    this.slider = document.querySelector(selector)
    this.prevButton = this.slider.querySelector('.prev-button')
    this.nextButton = this.slider.querySelector('.next-button')
    this.slides = Array.from(this.slider.querySelectorAll('img'))
    this.slideCount = this.slides.length
    this.slideIndex = 0
    this._initial()
  }

  _initial() {
    if (this.slideCount < 2) {
      this.prevButton.style.display = 'none'
      this.nextButton.style.display = 'none'
    } else {
      this.prevButton.addEventListener('click', this.showPreviousSlide)
      this.nextButton.addEventListener('click', this.showNextSlide)
      this._updateSlider()
    }
  }

  _updateSlider() {
    this.slides.forEach((slide, index) => {
      if (index === this.slideIndex) {
        slide.style.display = 'block';
      } else {
        slide.style.display = 'none';
      }
    })
  }

  showPreviousSlide = () => {
    this.slideIndex = (this.slideIndex - 1 + this.slideCount) % this.slideCount
    this._updateSlider()
  }

  showNextSlide = () => {
    this.slideIndex = (this.slideIndex + 1) % this.slideCount
    this._updateSlider()
  }
}