JavaScript實現(xiàn)無縫輪播圖的示例代碼
花費一個下午從0到1實現(xiàn)的輪播圖,當然還有很多需要改進的地方(歡迎提出需要改進的地方),等我再努力努力,將其封裝成一個組件。
上效果
一、實現(xiàn)過程
1)首先實現(xiàn)基本布局
<div class="carousel-container"> //圖片列表 <div class="carousel-list"></div> //上一張 <div class="carousel-arrow carousel-arrow-left"><</div> //下一張 <div class="carousel-arrow carousel-arrow-right">></div> //導(dǎo)航點 <div class="indicator"> <span class="active"></span> <span></span> <span></span> </div> </div>
2)主要樣式
簡單布局樣式就不說了,主要講如何將圖片橫向排列起來
先給容器設(shè)置相對定位,通過overflow將超出部分隱藏
.carousel-container { position: relative; width: 500px; height: 300px; /* overflow: hidden; */ background-color: #ccc; }
然后圖片列表設(shè)置相對定位和flex盒子,這樣每一個滑塊就橫向排列成一排了
.carousel-container .carousel-list { position: relative; display: flex; height: 100%; width: 100%; }
左右滑動按鈕通過絕對定位+transform的方式移動到兩邊,導(dǎo)航點也是一樣,就不一一詳說了
二、如何實現(xiàn)無縫呢 (重點來了)
思路:
1、先實現(xiàn)向后滾動無縫連接,將最后一張復(fù)制一份放到最前面,當滾動到最后一張時,再次滾動,將要滾動到第一張時,先取消過渡transition,瞬間跳到最前面復(fù)制的那張上,然后繼續(xù)運行動畫到第一張,這樣看起來就無縫了
2、向前滾動無縫連接,思路同上,復(fù)制第一張圖片放到最后,當滾動到第一張,再次滾動時,瞬間跳到最后復(fù)制的那張圖片上,繼續(xù)滾動到輪播圖的最后一張上。
主要代碼
先獲取到dom元素,currentIndex是當前輪播到的圖片下標
let currentIndex = 0; const doms = { carouselList: document.querySelector('.carousel-list'), arrowLeft: document.querySelector('.carousel-arrow-left'), arrowRight: document.querySelector('.carousel-arrow-right'), indicator: document.querySelectorAll('.indicator span') }
先初始化dom,復(fù)制圖片
// 復(fù)制第一張放最后,最后一張圖片放第一張之前 function init() { let lastImg = doms.carouselList.lastElementChild.cloneNode(true) let firstImg = doms.carouselList.firstElementChild.cloneNode(true) doms.carouselList.appendChild(firstImg) doms.carouselList.insertBefore(lastImg, doms.carouselList.firstElementChild) lastImg.style.position = 'absolute' lastImg.style.transform = 'translateX(-100%)' } //執(zhí)行一下 init()
實現(xiàn)到任意一張圖片的方法
function moveTo(index) { doms.carouselList.style.transform = `translateX(-${index * 100}%)` doms.carouselList.style.transition = '.5s' // 去掉導(dǎo)航點選中效果 let active = document.querySelector('.indicator span.active') active.classList.remove('active') // 添加選中效果 doms.indicator[index].classList.add('active') currentIndex = index }
給導(dǎo)航點綁定點擊跳轉(zhuǎn)事件
// 給導(dǎo)航點添加事件 doms.indicator.forEach((item, i) => { item.onclick = function () { moveTo(i); } })
給前后按鈕綁上執(zhí)行事件,判斷邊界圖片,及時取消過渡效果,瞬間跳到復(fù)制的圖片位置,調(diào)用moveTo到第一張或最后一張圖片上。
let indicatorLength = doms.indicator.length; function preSlide() { if (currentIndex === 0) { doms.carouselList.style.transition = 'none' doms.carouselList.style.transform = `translateX(-${indicatorLength * 100}%)` doms.carouselList.clientHeight moveTo(indicatorLength - 1) } else { moveTo(currentIndex - 1) } } function nextSlide() { if (currentIndex === doms.indicator.length - 1) { doms.carouselList.style.transition = 'none' doms.carouselList.style.transform = 'translateX(100%)' doms.carouselList.clientHeight moveTo(0) } else { moveTo(currentIndex + 1) } } doms.arrowLeft.onclick = function () { preSlide(); } doms.arrowRight.onclick = function () { nextSlide() }
最后使用定時器調(diào)用nertSlide方法就實現(xiàn)自動播放了
function start(time = 2000) { setInterval(() => { nextSlide() }, time) } start()
完整代碼
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> <style> * { margin: 0; padding: 0; box-sizing: border-box; } .carousel-container { margin: 0 auto; position: relative; width: 500px; height: 300px; /* overflow: hidden; */ background-color: #ccc; } .carousel-container .carousel-list { position: relative; display: flex; height: 100%; width: 100%; } .carousel-container .carousel-list .slide { flex: 0 0 100%; height: 100%; width: 100%; } .slide a { display: flex; justify-content: center; align-items: center; height: 100%; width: 100%; } .slide a img { width: 100%; } .carousel-container .carousel-arrow { display: none; position: absolute; width: 36px; height: 36px; border-radius: 50%; color: white; text-align: center; line-height: 36px; cursor: pointer; background-color: rgba(31, 45, 61, .2); } .carousel-container:hover .carousel-arrow { display: block; } .carousel-container:hover .carousel-arrow:hover { background-color: rgba(31, 45, 61, .4); } .carousel-container .carousel-arrow-left { top: 50%; left: 2%; transform: translateY(-50%); } .carousel-container .carousel-arrow-right { top: 50%; right: 2%; transform: translateY(-50%); } .carousel-container .indicator { display: flex; position: absolute; left: 50%; top: 90%; transform: translateX(-50%) } .carousel-container .indicator span { margin: 2px 5px; padding: 3px; width: 5px; height: 5px; border: 1px solid white; border-radius: 5px; } .active { background-color: #fff; } </style> </head> <body> <div class="carousel-container"> <div class="carousel-list"> <div class="slide"> <a href=""> <img src="https://ts4.cn.mm.bing.net/th?id=OIP-C.kB-Ovasi0GW67-rmwnAcwAHaEo&w=316&h=197&c=8&rs=1&qlt=90&o=6&dpr=1.25&pid=3.1&rm=2"> </a> </div> <div class="slide"> <a href=""> <img src="https://ts1.cn.mm.bing.net/th?id=OIP-C.QPH1IBosDYBqaU3O6wV3YAHaEo&w=316&h=197&c=8&rs=1&qlt=90&o=6&dpr=1.25&pid=3.1&rm=2"></a> </div> <div class="slide"> <a href=""> <img src="https://ts2.cn.mm.bing.net/th?id=OIP-C.P3NSGTdAYdyqy5zJpb5QXQHaEo&w=316&h=197&c=8&rs=1&qlt=90&o=6&dpr=1.25&pid=3.1&rm=2" alt=""></a> </div> </div> <div class="carousel-arrow carousel-arrow-left"><</div> <div class="carousel-arrow carousel-arrow-right">></div> <div class="indicator"> <span class="active"></span> <span></span> <span></span> </div> </div> </body> <script> window.onload = function () { const doms = { carouselList: document.querySelector('.carousel-list'), arrowLeft: document.querySelector('.carousel-arrow-left'), arrowRight: document.querySelector('.carousel-arrow-right'), indicator: document.querySelectorAll('.indicator span') } let currentIndex = 0; function moveTo(index) { doms.carouselList.style.transform = `translateX(-${index * 100}%)` doms.carouselList.style.transition = '.5s' // 去掉導(dǎo)航點選中效果 let active = document.querySelector('.indicator span.active') active.classList.remove('active') // 添加選中效果 doms.indicator[index].classList.add('active') currentIndex = index } // 給導(dǎo)航點添加事件 doms.indicator.forEach((item, i) => { item.onclick = function () { moveTo(i); } }) // 復(fù)制第一張放最后,最后一張圖片放第一張之前 function init() { let lastImg = doms.carouselList.lastElementChild.cloneNode(true) let firstImg = doms.carouselList.firstElementChild.cloneNode(true) doms.carouselList.appendChild(firstImg) doms.carouselList.insertBefore(lastImg, doms.carouselList.firstElementChild) lastImg.style.position = 'absolute' lastImg.style.transform = 'translateX(-100%)' } let indicatorLength = doms.indicator.length; function preSlide() { if (currentIndex === 0) { doms.carouselList.style.transition = 'none' doms.carouselList.style.transform = `translateX(-${indicatorLength * 100}%)` doms.carouselList.clientHeight moveTo(indicatorLength - 1) } else { moveTo(currentIndex - 1) } } function nextSlide() { if (currentIndex === doms.indicator.length - 1) { doms.carouselList.style.transition = 'none' doms.carouselList.style.transform = 'translateX(100%)' doms.carouselList.clientHeight moveTo(0) } else { moveTo(currentIndex + 1) } } doms.arrowLeft.onclick = function () { preSlide(); } doms.arrowRight.onclick = function () { nextSlide() } function start(time = 2000) { setInterval(() => { nextSlide() }, time) } start() init() } </script> </html>
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