Customization lazy CSS

Hello. This is the first time I’m doing this. Tell me if everything is correct.
Using the http article https://imagekit.io/blog/lazy-loading-images-complete-guide/

js is connected at the bottom of the page
<script src="/assets/2022/js/lazy/lazy.js"></script>

contains:

document.addEventListener("DOMContentLoaded", function() {
  var lazyloadImages;    

  if ("IntersectionObserver" in window) {
    lazyloadImages = document.querySelectorAll(".lazy");
    var imageObserver = new IntersectionObserver(function(entries, observer) {
      entries.forEach(function(entry) {
        if (entry.isIntersecting) {
          var image = entry.target;
          image.classList.remove("lazy");
          imageObserver.unobserve(image);
        }
      });
    });

    lazyloadImages.forEach(function(image) {
      imageObserver.observe(image);
    });
  } else {  
    var lazyloadThrottleTimeout;
    lazyloadImages = document.querySelectorAll(".lazy");
    
    function lazyload () {
      if(lazyloadThrottleTimeout) {
        clearTimeout(lazyloadThrottleTimeout);
      }    

      lazyloadThrottleTimeout = setTimeout(function() {
        var scrollTop = window.pageYOffset;
        lazyloadImages.forEach(function(img) {
            if(img.offsetTop < (window.innerHeight + scrollTop)) {
              img.src = img.dataset.src;
              img.classList.remove('lazy');
            }
        });
        if(lazyloadImages.length == 0) { 
          document.removeEventListener("scroll", lazyload);
          window.removeEventListener("resize", lazyload);
          window.removeEventListener("orientationChange", lazyload);
        }
      }, 20);
    }

    document.addEventListener("scroll", lazyload);
    window.addEventListener("resize", lazyload);
    window.addEventListener("orientationChange", lazyload);
  }
})

                <div id="bg-image" class="bg-layer-1 lazy" style="background-image: url(/assets/2022/images/column-bg-1.jpg);"></div>
                <div id="bg-image" class="bg-layer-2 lazy" style="background-image: url(/assets/2022/images/column-bg-2.jpg);"></div>

based on the article, I check in the console. How can I understand that there should be no images - if everything is correct?

Are there any errors on the Console tab?

Hello.yes, but this is a script of the vkontakte social network