Javascript Slider Effect01

<main>
    <section id="sliderType01">
        <div class="slider__wrap">
            <div class="slider__img">
                <div class="slider"><img src="img/slider_img02.jpg" alt="이미지1"></div>
                <div class="slider"><img src="img/slider_img03.jpg" alt="이미지2"></div>
                <div class="slider"><img src="img/slider_img04.jpg" alt="이미지3"></div>
                <div class="slider"><img src="img/slider_img05.jpg" alt="이미지4"></div>
                <div class="slider"><img src="img/slider_img06.jpg" alt="이미지5"></div>
            </div>
        </div>
    </section>
</main>

.slider__wrap {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
}
.slider__img {
    position: relative;
    width: 800px;
    height: 480px;
}
.slider {
    position: absolute;
    left: 0; top: 0;
}
.slider::before {
    position: absolute;
    left: 5px; top: 5px;
    background: rgba(0,0,0,0.4);
    color: #fff;
    padding: 5px 10px 3px;
}
.slider:nth-child(1)::before {content: '이미지1';}
.slider:nth-child(2)::before {content: '이미지2';}
.slider:nth-child(3)::before {content: '이미지3';}
.slider:nth-child(4)::before {content: '이미지4';}
.slider:nth-child(5)::before {content: '이미지5';}
.slider:nth-child(1) {z-index: 5;}
.slider:nth-child(2) {z-index: 4;}
.slider:nth-child(3) {z-index: 3;}
.slider:nth-child(4) {z-index: 2;}
.slider:nth-child(5) {z-index: 1;}

const sliderWrap = document.querySelector(".slider__wrap");
const sliderImg = document.querySelector(".slider__img");
const slider = document.querySelectorAll(".slider");

let currentIndex = 0;   //현재 보이는 이미지
let sliderCount = slider.length;    //이미지 갯수


setInterval(() => {
    let nextIndex = (currentIndex + 1) % 5;

    slider[currentIndex].style.opacity = "0"    //첫 번째 이미지를 안보이게
    slider[nextIndex].style.opacity = "1"       //두 번째 이미지를 보이게

    slider.forEach(slider => {
        slider.style.transition = "all 0.3s";
    })

    currentIndex = nextIndex;

}, 2000);