以下内容为学习记录，可以参考 MDN 原文。
环境
- vscode 1.46
- Microsoft Edge 83
html 模板
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>照片库</title>
<link rel="stylesheet" href="style.css">
</head>
<body>
<h1>照片库示例</h1>
<div class="full-img">
<img class="displayed-img" src="images/pic1.jpg">
<div class="overlay"></div>
<button class="dark">变暗</button>
</div>
<div class="thumb-bar">
</div>
<script src="main.js"></script>
</body>
</html>
样式表
h1 {
font-family: sans-serif;
text-align: center;
}
body {
640px;
margin: 0 auto;
}
.full-img {
position: relative;
display: block;
640px;
height: 480px;
}
.overlay {
position: absolute;
top: 0;
left: 0;
640px;
height: 480px;
background-color: rgba(0,0,0,0);
}
button {
border: 0;
background: rgba(150,150,150,0.6);
text-shadow: 1px 1px 1px white;
border: 1px solid #999;
position: absolute;
cursor: pointer;
top: 2px;
left: 2px;
}
.thumb-bar img {
display: block;
20%;
float: left;
cursor: pointer;
}
定义变量
const displayedImage = document.querySelector(".displayed-img");
const thumbBar = document.querySelector(".thumb-bar");
const btn = document.querySelector("button");
const overlay = document.querySelector(".overlay");
图片列表
/* 添加图片循环 */
for (let i = 1; i < 6; i++) {
const newImage = document.createElement("img");
newImage.setAttribute("src", "images/pic" + i + ".jpg");
thumbBar.appendChild(newImage);
}
切换图片
/* 切换图片 */
thumbBar.addEventListener("click", function(event) {
const src = event.target.getAttribute("src");
displayedImage.setAttribute("src", src);
});
变亮和变暗
addEventListener 和 removeEventListener 可以增加和删除事件。
/* 编写 变暗/变量 按钮功能 */
btn.addEventListener("click", function(event) {
const color = event.target.getAttribute("class");
if (color === "dark") {
btn.setAttribute("class", "light");
btn.textContent = "变亮";
overlay.style.backgroundColor = "rgba(0, 0, 0, 0.5)";
} else {
btn.setAttribute("class", "dark");
btn.textContent = "变暗";
overlay.style.backgroundColor = "rgba(0, 0, 0, 0)";
}
});