十五 Dom - 15.2 图片切换练习 - 《JavaScript 基础知识》

<!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>
        * {
            margin: 0;
            padding: 0;
        }
        #outer {
            width: 500px;
            margin: auto;
            text-align: center;
            background-color: pink;
        }
        img {
            width: 100%;
            height: 300px;
        }
    </style>
</head>
<body>
    <div id="outer">
        <p id="info"></p>
        <img src="./index/1.webp" alt="">
        <button id="prev">上一张</button>
        <button id="next">下一张</button>
    </div>
    <script>
        var imgArr = ['./index/1.webp', './index/2.webp', './index/3.webp', './index/4.webp', './index/5.webp', './index/6.webp']
        var prev = document.getElementById('prev')
        var next = document.getElementById('next')
        var img = document.getElementsByTagName('img')[0]
        var index = 0
        var info = document.getElementById('info')
        info.innerHTML = '一共有 '+(imgArr.length)+' 张图片，这是第 1 张图片'
        prev.onclick = function () {
            index--
            if (index < 0) {
                index = imgArr.length - 1
                img.alt = '图片'+(index+1)+''
            }
            img.src = imgArr[index]
            var info = document.getElementById('info')
            info.innerHTML = '一共有 ' + (imgArr.length) + ' 张图片，这是第 ' + (index+1) + ' 张图片'
        }
        next.onclick = function () {
            index++
            if (index > imgArr.length - 1) {
                index = 0
                img.alt = '图片'+(index+1)+''
            }
            img.src = imgArr[index]
            var info = document.getElementById('info')
            info.innerHTML = '一共有 ' + (imgArr.length) + ' 张图片，这是第 ' + (index+1) + ' 张图片'
        }
    </script>
</body>
</html>