JavaScript實現(xiàn)無縫輪播圖：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
.container {
position: relative;
width: 500px;
height: 400px;
border: 1px solid #fff;
margin: 20px auto;
overflow: hidden;
cursor: pointer;
}
.container .images img {
display: block;
float: left;
}
.container .dots {
position: absolute;
margin: 0 auto;
left: 0;
right: 0;
bottom: 10px;
background: rgba(255, 255, 255, .3);
padding: 5px;
border-radius: 20px;
}
.container .dots span {
margin: 2px;
width: 8px;
height: 8px;
display: block;
border-radius: 50%;
background: rgba(255, 255, 255, .5);
float: left;
}
.container .dots span.active {
background: #f40;
}
.container .arrow {
display: none;
}
.container:hover .arrow {
display: block;
}
.container .arrow .item {
width: 40px;
height: 40px;
background: rgba(255, 255, 255, .5);
color: #fff;
position: absolute;
top: 0;
bottom: 0;
margin: auto 0;
text-align: center;
line-height: 40px;
font-size: 20px;
}
.container .arrow .leftArrow {
left: 0;
border-radius: 0 20px 20px 0;
}
.container .arrow .rightArrow {
right: 0;
border-radius: 20px 0 0 20px;
}
</style>
</head>
<body>
<div class="container">
<div class="images">
</div>
<div class="dots">
</div>
<div class="arrow">
<div class="item leftArrow"><</div>
<div class="item rightArrow">></div>
</div>
</div>
<script>
var config = {
imgWidth: 500, //圖片寬度
dotWidth: 12, //小圓點寬度
imageArray: ["./image/5.jpg", "./image/1.jpg", "./image/2.jpg", "./image/3.jpg", "./image/4.jpg",
"./image/5.jpg", "./image/1.jpg"
], //存儲圖片路徑的數(shù)組
doms: {
images: document.querySelector(".images"), //存放圖片的dom
dots: document.querySelector(".dots"), //圓點的dom
leftArrow: document.querySelector(".item.leftArrow"), //左一張的dom
rightArrow: document.querySelector(".item.rightArrow") //右一張的dom
},
currentIndex: 2, //當(dāng)前展示的圖片下標(biāo)
timer: { //計時器配置
id: null, //計時器id
duration: 16, //每次切換圖片，運動的間隔時間
totalTime: 1000 //每次切換圖片，運動的時間總長
}
};
initImages();
initDots();
//初始化圖片元素
function initImages() {
//創(chuàng)建圖片元素
config.doms.images.style.width = config.imageArray.length * config.imgWidth + "px";
for (var i = 0; i < config.imageArray.length; i++) {
var img = document.createElement("img");
img.src = config.imageArray[i];
config.doms.images.appendChild(img);
}
//展示第一張圖片1.jpg
config.doms.images.style.marginLeft = -config.imgWidth * config.currentIndex + "px";
}
//創(chuàng)建圓點元素
function initDots() {
config.doms.dots.style.width = (config.imageArray.length - 2) * config.dotWidth + "px";
for (var i = 0; i < config.imageArray.length - 2; i++) {
var dot = document.createElement("span");
config.doms.dots.appendChild(dot);
}
config.doms.dots.children[config.currentIndex - 1].className = "active";
}
//點擊左箭頭、右箭頭、和圓點
config.doms.leftArrow.onclick = config.doms.rightArrow.onclick = config.doms.dots.onclick = function (e) {
if (e.target.tagName === "DIV" && e.target.classList.contains("leftArrow")) { //點擊左箭頭
var index = config.currentIndex - 1;//向左跳轉(zhuǎn)圖片的下標(biāo)
if(index === 0){//
index = 5;
}
jumpToImage(index, "left");
} else if (e.target.tagName === "DIV" && e.target.classList.contains("rightArrow")) { //點擊右箭頭
var index = config.currentIndex + 1;//向右跳轉(zhuǎn)圖片的下標(biāo)
if(index === 6){//
index = 1;
}
jumpToImage(index, "right");
} else if (e.target.tagName === "SPAN" && e.target.parentElement && e.target.parentElement.classList
.contains("dots")) { //點擊小圓點
var index = Array.from(config.doms.dots.children).indexOf(e.target) + 1;
jumpToImage(index, (index > config.currentIndex) ? "right" : "left");
}
}
//跳轉(zhuǎn)到哪張圖片
function jumpToImage(index, direction) { //index:下一張圖片的下標(biāo)(1,25);direction方向(1.left:左;2.right:右);
if (index === config.currentIndex) { //若要跳轉(zhuǎn)的圖片下標(biāo)和當(dāng)前下標(biāo)一樣，不執(zhí)行
return;
}
if (!direction) { //方向默認(rèn)：為右
direction = "right";
}
//要運動到的目標(biāo)marginLeft
var newMarginLeft = -index * config.imgWidth;
//圖片切換
//config.doms.images.style.marginLeft = newMarginLeft + "px";
autoPlay();
//圓點也自動切換
for (var i = 0; i < config.doms.dots.children.length; i++) {
config.doms.dots.children[i].classList.remove("active");
}
config.doms.dots.children[index - 1].className = "active";
//切換完成后，改變當(dāng)前圖片下標(biāo)
config.currentIndex = index;
//圖片漸變動畫,一點一點的改變marginLeft
function autoPlay() {
stopPlay(); //在播放輪播圖之前，把上次的動畫先停掉
//當(dāng)前的marginLeft
var currentMarginLeft = parseFloat(window.getComputedStyle(config.doms.images).marginLeft);
//圖片總長度，不能算第一張和最后一張，這兩張是額外增加重復(fù)的兩張
var allImagesLength = (config.imageArray.length - 2) * config.imgWidth;
//1.計算運動總次數(shù)
var frequency = Math.ceil(config.timer.totalTime / config.timer.duration);
var currentNum = 0; //當(dāng)前運動的次數(shù)
//2.計算運動的總距離
var allDistance = 0;
if (direction == "left") { //向左運動
if (newMarginLeft > currentMarginLeft) { //目標(biāo)marginLeft > 當(dāng)前marginLeft
//總距離 = 目標(biāo)marginLeft - 當(dāng)前marginLeft
allDistance = newMarginLeft - currentMarginLeft;
} else {
//總距離 = 圖片總長度 - |目標(biāo)marginLeft - 當(dāng)前marginLeft|
allDistance = allImagesLength - Math.abs(newMarginLeft - currentMarginLeft);
}
} else { //向右運動
if (newMarginLeft < currentMarginLeft) { //目標(biāo)marginLeft < 當(dāng)前marginLeft
//總距離 = 目標(biāo)marginLeft - 當(dāng)前marginLeft
allDistance = newMarginLeft - currentMarginLeft;
} else { //目標(biāo)marginLeft > 當(dāng)前marginLeft
//總距離 = -(圖片總長度 - |目標(biāo)marginLeft - 當(dāng)前marginLeft|)
allDistance = -(allImagesLength - Math.abs(newMarginLeft - currentMarginLeft));
}
}
//3.計算每次運動改變的距離
var everyDistance = allDistance / frequency; //每次運動距離 = 運動總距離 / 運動總次數(shù)
config.timer.id = setInterval(function () {
//改變圖片的marginLeft
currentMarginLeft += everyDistance;
//若圖片向右移動到額外的第一張（即數(shù)組中最后一張圖片)
if (direction === "right" && Math.floor(Math.abs(currentMarginLeft)) > allImagesLength) {
currentMarginLeft += allImagesLength; //圖片瞬間挪回第一張圖片對應(yīng)的位置
} else if (direction === "left" && Math.ceil(Math.abs(currentMarginLeft)) < config
.imgWidth) { //若圖片向左移動到額外的最后一張（即數(shù)組中第一張圖片)
currentMarginLeft -= allImagesLength; //圖片瞬間挪回最后一張圖片對應(yīng)的位置
}
config.doms.images.style.marginLeft = currentMarginLeft + "px";
currentNum++; //每執(zhí)行一次，當(dāng)前運動次數(shù)++
if (currentNum === frequency) { //達(dá)到運動總次數(shù)，停止運動
stopPlay();
}
}, config.timer.duration);
}
//停止播放
function stopPlay() {
clearInterval(config.timer.id);
config.timer.id = null;
}
}
</script>
</body>
</html>
效果展示：
最后一張圖片切換第一張圖片的效果
圖片數(shù)組存儲一共七張圖片，但是1.jpg 和 5.jpg存放了兩次，用來銜接。這樣從5.jpg切換到1.jpg的時候不會出現(xiàn)斷檔，五張圖片的寬高是500 X 200
制作無縫輪播圖的難點：
計算運動的總距離
向左運動，目標(biāo)margin-left 和 當(dāng)前的margin-left
目標(biāo)marginLeft > 當(dāng)前marginLeft //總距離 = 目標(biāo)marginLeft - 當(dāng)前marginLeft
目標(biāo)marginLeft < 當(dāng)前marginLeft //總距離 = 圖片總長度 - |目標(biāo)marginLeft - 當(dāng)前marginLeft|
向右運動，目標(biāo)margin-left 和 當(dāng)前的margin-left
目標(biāo)marginLeft < 當(dāng)前marginLeft //總距離 = 目標(biāo)marginLeft - 當(dāng)前marginLeft
目標(biāo)marginLeft > 當(dāng)前marginLeft //總距離 = -(圖片總長度 - |目標(biāo)marginLeft - 當(dāng)前marginLeft|)
