演示地址

Expanding Cards (50projects50days.com)

实现思路

结构样式方面主要是flex弹性布局，并且添加过渡效果。
js部分首先获取所有box节点然后遍历添加click事件，添加、移除active来实现切换效果。

代码

html结构

<!DOCTYPE html>
<html lang="zh-CN">

<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>扩展卡片</title>
    <link rel="stylesheet" href="style.css">
</head>

<body>
    <div class="container">
        <div class="box active" style="background-image: url('./image/1.jpg')">
            <h3>人间四月芳菲尽,山寺桃花始盛开。</h3>
        </div>
        <div class="box" style="background-image: url('./image/2.jpg')">
            <h3>重湖叠巘清嘉，有三秋桂子，十里荷花。</h3>
        </div>
        <div class="box" style="background-image: url('./image/3.jpg')">
            <h3>月落乌啼霜满天，江枫渔火对愁眠。</h3>
        </div>
        <div class="box" style="background-image: url('./image/4.jpg')">
            <h3>天寒霜雪繁，游子有所之。</h3>
        </div>
    </div>
    <script src="./script.js"></script>
</body>

</html>

css样式

* {
    box-sizing: border-box;
}

body {
    /* 弹性布局垂直居中 */
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: #f8f1e7;
}

.container {
    display: flex;
    width: 90vw;
}

.box {
    /* 子元素绝对定位，父元素相对定位 */
    position: relative;
    /* flex元素在主轴上的比例 */
    flex: 0.5;
    height: 80vh;
    margin: 10px;
    border-radius: 50px;
    box-shadow: 1px 2px 10px 0px #b7b7b7;
    /* 调整背景图片 */
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    color: #fff;
    cursor: pointer;
    /* 过渡效果 */
    transition: flex 0.8s ease-in;
}

.box h3 {
    /* 绝对定位 */
    position: absolute;
    right: 20px;
    bottom: 20px;
    margin: 0;
    font-size: 28px;
    opacity: 0;
    transition: opacity 0.2s ease-in 0.4s;
}

.active {
    /* 增加元素在主轴上的比例 */
    flex: 5;
}

.active h3 {
    opacity: 1;
}

js行为

// 查询所有.box节点
const nodes = document.querySelectorAll('.box');
// console.log(nodes);
// 遍历添加click事件
nodes.forEach(node => {
    node.addEventListener('click', () => {
        removeActiveClassses();
        // 给当前对象添加acticve
        node.classList.add('active');
    })
});
// 移除所有节点active
function removeActiveClassses() {
    nodes.forEach(node => {
        node.classList.remove('active');
    })
}

参考资料：50 Projects 50 Days | Traversy Media
50 unique mini-projects to sharpen your HTML, CSS & JavaScript skills