JavaScript Slider Effect01

<main>
    <section id="sliderType01">
        <div class="slider__wrap">
            <div class="slider__img">
                <div class="slider"><img src="img/img01.jpg" alt="이미지1"></div>
                <div class="slider"><img src="img/img02.jpg" alt="이미지2"></div>
                <div class="slider"><img src="img/img03.jpg" alt="이미지3"></div>
                <div class="slider"><img src="img/img04.jpg" alt="이미지4"></div>
                <div class="slider"><img src="img/img05.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"    // 첫번째 이미지를 안보이게
    slider[nextIndex].style.opacity = "1"       // 두번째 이미지를 보이게

    slider.forEach(slider => {
        slider.style.transition = "all 0.3s"
    })
    //console.log("currentIndex :" + currentIndex)
    //console.log("nextIndex :" + nextIndex)
    currentIndex = nextIndex;
}, 2000);