JS原生带缩略图的图片切换效果

2020-11-27 来源：汇智旅游网

本例中用到的 moveElement(elementID,final_x,final_y,interval)是来自《JavaScript DOM编程艺术（中文第二版）》一书第10章中有一段代码。（可以直接baidu）

左边是banner图，右边是缩略图，当鼠标滑入缩略图时，也会切换图片。

一、这段是html代码，可以直接拷贝，需要自己准备相同大小的banner图，例中图片都是500x300

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <meta http-equiv="X-UA-Compatible" content="ie=edge">
 <title>图片轮播</title>
 <script src="./js.js"></script>
 <style>
 * {
 margin: 0;
 padding: 0;
 word-break: break-all;
 }
 body {
 background: #FFF;
 color: #333;
 font: 12px/1.6em Helvetica, Arial, sans-serif;
 }
 a {
 color: #0287CA;
 text-decoration: none;
 }
 a:hover {
 text-decoration: underline;
 }
 ul,
 li {
 list-style: none;
 }
 fieldset,
 img {
 border: none;
 }
 legend {
 display: none;
 }
 em,
 strong,
 cite,
 th {
 font-style: normal;
 font-weight: normal;
 }
 input,
 textarea,
 select,
 button {
 font: 12px Helvetica, Arial, sans-serif;
 }
 table {
 border-collapse: collapse;
 }
 html {
 overflow: -moz-scrollbars-vertical;
 }
 #ifocus {
 width: 620px;
 height: 320px;
 margin: 20px;
 border: 1px solid #DEDEDE;
 background: #F8F8F8;
 }
 #ifocus_pic {
 display: inline;
 position: relative;
 float: left;
 width: 500px;
 height: 300px;
 overflow: hidden;
 margin: 10px 0 0 10px;
 }
 #ifocus_piclist {
 position: absolute;
 }
 #ifocus_piclist li {
 width: 500px;
 height: 300px;
 overflow: hidden;
 }
 #ifocus_piclist img {
 width: 500px;
 height: 300px;
 }
 #ifocus_btn {
 display: inline;
 float: right;
 width: 94px;
 margin: 9px 9px 0 0;
 }
 #ifocus_btn li {
 width: 94px;
 height: 57px;
 cursor: pointer;
 opacity: 0.5;
 -moz-opacity: 0.5;
 filter: alpha(opacity=50);
 }
 #ifocus_btn img {
 width: 80px;
 height: 50px;
 margin: 7px 0 0 11px;
 }
 #ifocus_btn .current {
 /* background: url(i/ifocus_btn_bg.gif) no-repeat; */
 opacity: 1;
 -moz-opacity: 1;
 filter: alpha(opacity=100);
 }
 </style>
</head>
<body>
 <div id="ifocus">
 <div id="ifocus_pic">
 <div id="ifocus_piclist" style="left:0; top:0;">
 <ul>
 <li><a href="#"><img src="./images/1.jpg" alt="" /></a></li>
 <li><a href="#"><img src="./images/2.jpg" alt="" /></a></li>
 <li><a href="#"><img src="./images/3.jpg" alt="" /></a></li>
 <li><a href="#"><img src="./images/4.jpg" alt="" /></a></li>
 <li><a href="#"><img src="./images/5.jpg" alt="" /></a></li>
 </ul>
 </div>
 </div>
 <div id="ifocus_btn">
 <ul>
 <li class="current"><img src="./images/1.jpg" alt="" /></li>
 <li><img src="./images/2.jpg" alt="" /></li>
 <li><img src="./images/3.jpg" alt="" /></li>
 <li><img src="./images/4.jpg" alt="" /></li>
 <li><img src="./images/5.jpg" alt="" /></li>
 </ul>
 </div>
 </div>
</body>
</html>

二、这段是js代码，其中用到了几个经典的js代码。在js中需要修改对应的id名字、图片移动的尺寸等。

function $(id) {
 return document.getElementById(id);
}
function addLoadEvent(func) {
 var oldonload = window.onload;
 if (typeof window.onload != 'function') {
 window.onload = func;
 } else {
 window.onload = function () {
 oldonload();
 func();
 }
 }
}
function moveElement(elementID, final_x, final_y, interval) {
 if (!document.getElementById) return false;
 if (!document.getElementById(elementID)) return false;
 var elem = document.getElementById(elementID);
 if (elem.movement) {
 clearTimeout(elem.movement);
 }
 if (!elem.style.left) {
 elem.style.left = "0px";
 }
 if (!elem.style.top) {
 elem.style.top = "0px";
 }
 var xpos = parseInt(elem.style.left);
 var ypos = parseInt(elem.style.top);
 if (xpos == final_x && ypos == final_y) {
 return true;
 }
 if (xpos < final_x) {
 var dist = Math.ceil((final_x - xpos) / 10);
 xpos = xpos + dist;
 }
 if (xpos > final_x) {
 var dist = Math.ceil((xpos - final_x) / 10);
 xpos = xpos - dist;
 }
 if (ypos < final_y) {
 var dist = Math.ceil((final_y - ypos) / 10);
 ypos = ypos + dist;
 }
 if (ypos > final_y) {
 var dist = Math.ceil((ypos - final_y) / 10);
 ypos = ypos - dist;
 }
 elem.style.left = xpos + "px";
 elem.style.top = ypos + "px";
 var repeat = "moveElement('" + elementID + "'," + final_x + "," + final_y + "," + interval + ")";
 elem.movement = setTimeout(repeat, interval);
}
function classNormal(iFocusBtnID) {
 var iFocusBtns = $(iFocusBtnID).getElementsByTagName('li');
 for (var i = 0; i < iFocusBtns.length; i++) {
 iFocusBtns[i].className = 'normal';
 }
}
function classCurrent(iFocusBtnID, n) {
 var iFocusBtns = $(iFocusBtnID).getElementsByTagName('li');
 iFocusBtns[n].className = 'current';
}
function iFocusChange() {
 if (!$('ifocus')) return false;
 $('ifocus').onmouseover = function () {
 atuokey = true
 };
 $('ifocus').onmouseout = function () {
 atuokey = false
 };
 var iFocusBtns = $('ifocus_btn').getElementsByTagName('li');
 var listLength = iFocusBtns.length;
 iFocusBtns[0].onmouseover = function () {
 moveElement('ifocus_piclist', 0, 0, 5);
 classNormal('ifocus_btn');
 classCurrent('ifocus_btn', 0);
 }
 if (listLength >= 2) {
 iFocusBtns[1].onmouseover = function () {
 moveElement('ifocus_piclist', 0, -300, 5);
 classNormal('ifocus_btn');
 classCurrent('ifocus_btn', 1);
 }
 }
 if (listLength >= 3) {
 iFocusBtns[2].onmouseover = function () {
 moveElement('ifocus_piclist', 0, -600, 5);
 classNormal('ifocus_btn');
 classCurrent('ifocus_btn', 2);
 }
 }
 if (listLength >= 4) {
 iFocusBtns[3].onmouseover = function () {
 moveElement('ifocus_piclist', 0, -900, 5);
 classNormal('ifocus_btn');
 classCurrent('ifocus_btn', 3);
 }
 }
 if (listLength >= 5) {
 iFocusBtns[4].onmouseover = function () {
 moveElement('ifocus_piclist', 0, -1200, 5);
 classNormal('ifocus_btn');
 classCurrent('ifocus_btn', 4);
 }
 }
}
setInterval('autoiFocus()', 3000);
var atuokey = false;
function autoiFocus() {
 if (!$('ifocus')) return false;
 if (atuokey) return false;
 var focusBtnList = $('ifocus_btn').getElementsByTagName('li');
 var listLength = focusBtnList.length;
 for (var i = 0; i < listLength; i++) {
 if (focusBtnList[i].className == 'current') var currentNum = i;
 }
 if (currentNum == 0 && listLength != 1) {
 moveElement('ifocus_piclist', 0, -300, 5);
 classNormal('ifocus_btn');
 classCurrent('ifocus_btn', 1);
 }
 if (currentNum == 1 && listLength != 2) {
 moveElement('ifocus_piclist', 0, -600, 5);
 classNormal('ifocus_btn');
 classCurrent('ifocus_btn',2);
 }
 if (currentNum == 2 && listLength != 3) {
 moveElement('ifocus_piclist', 0, -900, 5);
 classNormal('ifocus_btn');
 classCurrent('ifocus_btn',3);
 }
 if (currentNum == 3) {
 moveElement('ifocus_piclist', 0, -1200, 5);
 classNormal('ifocus_btn');
 classCurrent('ifocus_btn', 4);
 }
 if (currentNum == 4) {
 moveElement('ifocus_piclist', 0, 0, 5);
 classNormal('ifocus_btn');
 classCurrent('ifocus_btn',0);
 }
}
addLoadEvent(iFocusChange);

效果如下图

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JS原生带缩略图的图片切换效果