网站质量分析双十二优惠活动

<!-- 使用懒加载技术 -->
<img src="placeholder.jpg" data-src="real-image.jpg" class="lazyload">

<script>
document.addEventListener("DOMContentLoaded", function() {
  var lazyImages = [].slice.call(document.querySelectorAll("img.lazyload"));
  if ("IntersectionObserver" in window) {
    let lazyImageObserver = new IntersectionObserver(function(entries, observer) {
      entries.forEach(function(entry) {
        if (entry.isIntersecting) {
          let lazyImage = entry.target;
          lazyImage.src = lazyImage.dataset.src;
          lazyImage.classList.remove("lazyload");
          lazyImageObserver.unobserve(lazyImage);
        }
      });
    });
    lazyImages.forEach(function(lazyImage) {
      lazyImageObserver.observe(lazyImage);
    });
  }
});
</script>

# 使用Nginx进行负载均衡配置
upstream backend {
  server backend1.example.com;
  server backend2.example.com;
  server backend3.example.com;
}

server {
  listen 80;
  location / {
    proxy_pass http://backend;
  }
}