JavaScript Slider Effect01

<main>
    <section>
        <div class="slider__wrap">
            <div class="slider__img">
                <div class="slider"><img src="img/arch01.jpg" alt="이미지1"<>/div>
                <div class="slider"><img src="img/arch02.jpg" alt="이미지2"<>/div>
                <div class="slider"><img src="img/arch03.jpg" alt="이미지3"<>/div>
                <div class="slider"><img src="img/arch04.jpg" alt="이미지4"<>/div>
                <div class="slider"><img src="img/arch05.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__img .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'    //0 1 2 3 4 0 1 2 3 4 0

        slider[currentIndex].style.opacity = "0";   //첫번째 이미지를 안 보이게
        slider[nextIndex].style.opacity = "1";      //두번째 이미지를 안 보이게

        //각 슬라이더마다 효과 주기
        slider.toEach(slider => {
            slider.style.transition = "all 0.3s";
        })

        currentIndex = nextIndex;   //nextIndex에 currentIndex를 대입
    }, '2000');