阿超 > 图片懒加载

图片懒加载

2022-01-02

前端

如果你只读每个人都在读的书，你也只能想到每个人都能想到的事。——村上春树

首先贴代码：

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<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			.ruben {
				width: 400px;
				height: 300px;
				background-color: #e8e8e8
			}

			.ruben img {
				width: 100%;
				height: 100%;
			}
		</style>
	</head>
	<body>

		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3059_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3058_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3057_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3055_3.jpg"></div>
		<div class="ruben"><img src="https://VampireAchao.github.io/imgs/preview/3056_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3054_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3053_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3052_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3051_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3050_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3049_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3048_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3047_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3046_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3045_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3044_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3043_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3042_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3041_3.jpg"></div>
		<div class="ruben"><img data-src="https://VampireAchao.github.io/imgs/preview/3040_3.jpg"></div>

		<script type="text/javascript">
			// 获取需要懒加载的元素
			let lazyLoadImgs = document.querySelectorAll("img")

			function lazyLoad() {
				// 屏幕可视区域高度
				let clientHeight = document.documentElement.clientHeight
				// 遍历图片
				lazyLoadImgs.forEach(e => {
					if (!e.src) {
						// 获取元素界面信息(宽高位置等)
						let rect = e.getBoundingClientRect()
						if (rect.top < clientHeight) {
							// 如果当前图片处于可视区域,则将data-src中的值放入src
							e.src = e.dataset.src
						}
					}
				})
				// 滚动时加载
				window.onscroll ??= lazyLoad
			}
			lazyLoad()
		</script>
	</body>
</html>

在你们自己的代码中使用方式也很简单：

首先复制这串js：

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// 获取需要懒加载的元素
let lazyLoadImgs = document.querySelectorAll("img")

function lazyLoad() {
	// 屏幕可视区域高度
	let clientHeight = document.documentElement.clientHeight
	// 遍历图片
	lazyLoadImgs.forEach(e => {
		if (!e.src) {
			// 获取元素界面信息(宽高位置等)
			let rect = e.getBoundingClientRect()
			if (rect.top < clientHeight) {
				// 如果当前图片处于可视区域,则将data-src中的值放入src
				e.src = e.dataset.src
			}
		}
	})
	// 滚动时加载
	window.onscroll ??= lazyLoad
}
lazyLoad()

然后在你们页面中使用，这里需要将你们原来页面上img标签的src改为data-src，这样在元素处于可视区域,则将data-src中的值放入src，然后达到懒加载的效果