图片懒加载

懒加载（Lazy Loading）是一种计算机编程技术，用于延迟初始化对象或资源，直到它们实际需要使用时才进行加载或初始化。这种技术可以提高程序的启动速度和性能，减少不必要的资源消耗，特别是在处理大型数据集或资源密集型任务时。

图片懒加载

1.使用intersectionObserver(交叉观察器)处理图片加载问题

相关链接：IntersectionObserver介绍
代码部分
html部分

<p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>

  <img data-src="https://q6.itc.cn/q_70/images03/20240126/4eaa7950e4214e8e83965f851318a03d.jpeg" alt="Image">
  <img data-src="https://q6.itc.cn/q_70/images03/20240126/4eaa7950e4214e8e83965f851318a03d.jpeg" alt="Image">
  <img data-src="https://q6.itc.cn/q_70/images03/20240126/4eaa7950e4214e8e83965f851318a03d.jpeg" alt="Image">
  <img data-src="https://q6.itc.cn/q_70/images03/20240126/4eaa7950e4214e8e83965f851318a03d.jpeg" alt="Image">
  <img data-src="https://q6.itc.cn/q_70/images03/20240126/4eaa7950e4214e8e83965f851318a03d.jpeg" alt="Image">
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>
  <p>Lazy loading, also known as deferred loading or delay loading, serves several critical purposes in various
    computing contexts. Here is an overview of its roles in different scenarios:In Web Design</p>

js部分

 <script>
    // 获取图片dom
    let images = document.querySelectorAll('img');

    // 创建intersectionObserver实例
    const imagesObserver = new IntersectionObserver(entries => {
      entries.forEach(entry => {
        // 1.判断图片是否显示
        if (entry.isIntersecting) {
          // 2.获取原img的src内容
          const image = entry.target;
          const data_src = image.getAttribute('data-src');
          // 3.设置其src属性
          image.setAttribute('src', data_src)
          // 4.取消观察
          imagesObserver.unobserve(image);
        }

      })
    })

    // 观察所有图片
    images.forEach(item => {
      imagesObserver.observe(item);
    })
  </script>

封装的lazyload.js

// 1.获取图片集合
const images = document.querySelectorAll('img')
// 2.实例intersectionObserver
const imagesObserver = new IntersectionObserver(entries => {
  entries.forEach(entry => {
    if (entry.isIntersecting) {
      const image = entry.target;
      const data_src = image.getAttribute('data-src');
      image.setAttribute('src', data_src);
      imagesObserver.unobserve(image)
    }
  })
})
// 3.为图片创建实例
images.forEach(item => {
  imagesObserver.observe(item)
})

2.使用img标签中的loading属性设置成为lazy,注意的时，该属性在一些浏览器中不兼容。

  <img loading="lazy" src="https://q6.itc.cn/q_70/images03/20240126/4eaa7950e4214e8e83965f851318a03d.jpeg" alt="Image">

3.添加通过监听滚动事件进行处理

window.addEventListener('scroll', lazyLoadImages);
function lazyLoadImages() {
  const images = document.querySelectorAll('img[data-src]');
  images.forEach(image => {
    if (image.getBoundingClientRect().top < window.innerHeight) {
      image.src = image.getAttribute('data-src');
    }
  });
}