这是我在github 上发现的一个原生js挑战项目，由于是js小白，希望通过这次的项目加深对js的理解
第五天的挑战是点击任意一张图片，图片展开，上端和下端显示出文字，再次点击，图片缩回，字消失
day5效果图
CSS部分（由于做完这些，我对flexbox 还不是特别的熟练，明天准备做一做阮一峰大神的flexbox实例）如有不足，下次改进
本次挑战主要难点在css部分的flexBox部分
布局的传统解决方案，基于盒状模型，依赖 display属性+ position属性 + float属性。它对于那些特殊布局非常不方便，比如，垂直居中就不容易实现。
- Flex Container(Parent)
- display:flex 将其设置为弹性盒子
- justify-content: center;沿主轴的的对齐方式为中部
- flex-direction: column;排列方式为纵向
- Flex Item(children)
flex属性是flex-grow(伸展值),flex-shrink(可接受的压缩值)和flex-basis（元素默认的尺寸值）的简写，默认值为0 1 auto。后两个属性可选。
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Flex Panels</title>
<link href='https://fonts.googleapis.com/css?family=Amatic+SC' rel='stylesheet' type='text/css'>
</head>
<body>
<style>
html {
box-sizing: border-box;
background:#ffc600;
font-family:'helvetica neue';
font-size: 20px;
font-weight: 200;
}
body {
margin: 0;
}
*, *:before, *:after {
box-sizing: inherit;
}
.panels {
min-height:100vh;
overflow: hidden;
display: flex;
}
.panel {
background:#6B0F9C;
box-shadow:inset 0 0 0 5px rgba(255,255,255,0.1);
color:white;
text-align: center;
align-items:center;
/* Safari transitionend event.propertyName === flex */
/* Chrome + FF transitionend event.propertyName === flex-grow */
transition:
font-size 0.7s cubic-bezier(0.61,-0.19, 0.7,-0.11),
flex 0.7s cubic-bezier(0.61,-0.19, 0.7,-0.11),
background 0.2s;
font-size: 20px;
background-size:cover;
background-position:center;
flex: 1;
justify-content: center;
display: flex;
flex-direction: column;
}
.panel1 { background-image:url(https://source.unsplash.com/gYl-UtwNg_I/1500x1500); }
.panel2 { background-image:url(https://source.unsplash.com/1CD3fd8kHnE/1500x1500); }
.panel3 { background-image:url(https://images.unsplash.com/photo-1465188162913-8fb5709d6d57?ixlib=rb-0.3.5&q=80&fm=jpg&crop=faces&cs=tinysrgb&w=1500&h=1500&fit=crop&s=967e8a713a4e395260793fc8c802901d); }
.panel4 { background-image:url(https://source.unsplash.com/ITjiVXcwVng/1500x1500); }
.panel5 { background-image:url(https://source.unsplash.com/3MNzGlQM7qs/1500x1500); }
/* Flex Items */
.panel > * {
margin:0;
width: 100%;
transition:transform 0.5s;
flex: 1 0 auto;
display:flex;
justify-content: center;
align-items: center;
}
.panel > *:first-child { transform: translateY(-100%); }
.panel.open-active > *:first-child { transform: translateY(0); }
.panel > *:last-child { transform: translateY(100%); }
.panel.open-active > *:last-child { transform: translateY(0); }
.panel p {
text-transform: uppercase;
font-family: 'Amatic SC', cursive;
text-shadow:0 0 4px rgba(0, 0, 0, 0.72), 0 0 14px rgba(0, 0, 0, 0.45);
font-size: 2em;
}
.panel p:nth-child(2) {
font-size: 4em;
}
.panel.open {
flex: 5;
font-size:40px;
}
</style>
<div class="panels">
<div class="panel panel1">
<p>Hey</p>
<p>Let's</p>
<p>Dance</p>
</div>
<div class="panel panel2">
<p>Give</p>
<p>Take</p>
<p>Receive</p>
</div>
<div class="panel panel3">
<p>Experience</p>
<p>It</p>
<p>Today</p>
</div>
<div class="panel panel4">
<p>Give</p>
<p>All</p>
<p>You can</p>
</div>
<div class="panel panel5">
<p>Life</p>
<p>In</p>
<p>Motion</p>
</div>
</div>
</body>
</html>
JS 部分
- 获取所有类名为 panel 的元素
- 为其添加 click 事件监听，编写触发事件调用的函数
- --为其添加 transitionend 事件监听，编写调用的函数
const panels = document.querySelectorAll('.panel');
function toggleOpen() {
console.log('Hello');
this.classList.toggle('open');
}
function toggleActive(e) {
console.log(e);
console.log(e.propertyName);
if (e.propertyName.includes('flex')) {
this.classList.toggle('open-active');
}
}
panels.forEach(panel => panel.addEventListener('click', toggleOpen));
panels.forEach(panel => panel.addEventListener('transitionend', toggleActive));
这次js大部分内容都在以前的挑战中出现过，唯一出现的新知识点是toggle()，其为切换功能，也就是说如果存在这个类就移除，如果不存在就添加
以上就是我在day5中学到的知识，这里我同样参考了soyaine的中文指南，感谢
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