移动端— Touch事件轮播图

　　　虽然 以前也写过手机端页面 。当时用的jquery moblie 框架。啥也不懂 就知道复制粘贴出效果 不敢改内部样式。现在呢  了解手机端原理 一些基本的概念 视口 缩放 后 。再去想以前写的页面 套框架 显然得心应手了不少。

手机移动端轮播 原生js

代码：

let banner = document.querySelector('.jd_banner')
    let imgbox = banner.querySelector('ul:first-of-type')//第一个ul
    let first = imgbox.querySelector('li:first-of-type')
    let last = imgbox.querySelector('li:last-of-type')
    //插入
    // 最后的位置           //复制一个
    imgbox.appendChild(first.cloneNode(true))
    //开始的位置
    imgbox.insertBefore(last.cloneNode(true), imgbox.firstChild)
    let lilist = imgbox.children
    let bannerWidth = banner.offsetWidth;
    imgbox.style.width = lilist.length * bannerWidth + 'px'
    for (let i = 0; i < lilist.length; i++) {
        lilist[i].style.width = imgbox.offsetWidth / lilist.length + 'px'
    }
    imgbox.style.left = -bannerWidth + 'px'

    let index = 1;
    //屏幕大小改变
    window.onresize = function () {
        bannerWidth = banner.offsetWidth;
        imgbox.style.width = lilist.length * bannerWidth + 'px'
        for (let i = 0; i < lilist.length; i++) {
            lilist[i].style.width = imgbox.offsetWidth / lilist.length + 'px'
        }
        imgbox.style.left = (-index * bannerWidth) + 'px'

    }
    let bannerIndex = document.querySelector('.jd_bannerIndex')

    function active(i) {
        for (let j = 0; j < bannerIndex.children.length; j++) {
            bannerIndex.children[j].className = ''
        }
        bannerIndex.children[i].className = 'active'
    }
    function banntime(){
        index++
        imgbox.style.transition = 'left 0.5s ease-in-out'

        imgbox.style.left = (-index * bannerWidth) + 'px'
        if (index == lilist.length - 1) {
            active(0)
            index = 1
            setTimeout(function () {

                imgbox.style.transition = 'none'

                active(index - 1)
                imgbox.style.left = (-index * bannerWidth) + 'px'

            }, 500)
        }
        active(index - 1)
    }
    let bannerInt = setInterval(banntime, 2000)

    let startX, moveX, distanceX;

    imgbox.addEventListener('touchstart', function (e) {
        startX = e.targetTouches[0].clientX
        clearInterval(bannerInt)
    })

    imgbox.addEventListener('touchmove', function (e) {
        moveX = e.targetTouches[0].clientX
        distanceX = moveX - startX
        imgbox.style.left = (-index * bannerWidth + distanceX) + 'px'
    })

    imgbox.addEventListener('touchend', function (e) {
        imgbox.style.transition = 'left 0.5s ease-in-out'
        let drX = distanceX % bannerWidth
        if (Math.abs(drX) > bannerWidth / 2) {
            if (drX > 0) {
                index--
            } else {
                index++
            }
            if (index == 0) {
                index = 8
                imgbox.style.transition = 'none'
            }
            if (index == lilist.length - 1) {
                index = 1
                imgbox.style.transition = 'none'
            }
        }
        active(index - 1)
        imgbox.style.left = (-index * bannerWidth) + 'px'
        bannerInt=setInterval(banntime,2000)

    })

　　效果：

总结 ：

 不管什么框架库，还是基本很重要 了解原理 才能得心应手