How to use JavaScript to scale content that automatically loads when scrolling to the bottom of the page while maintaining the aspect ratio effect?

JavaScript How to achieve scrolling to the bottom of the page and automatically load the content to scale and maintain the aspect ratio effect?

In modern web design, scrolling to the bottom of the page to automatically load more content has become a common functional requirement. When the loaded content contains images, we often want these images to maintain their original aspect ratio. This article will introduce how to use JavaScript to implement this function and provide corresponding code examples for reference.

First, we need to get the scroll position of the page. In JavaScript, you can use the scroll event to monitor the page scrolling action, and obtain the vertical distance of the current page scrolling through the window.scrollY property.

Next, we can determine whether the scroll has reached the bottom by comparing the scroll position of the current page with the total height of the page. If the scroll position of the current page plus the visible height of the window is greater than or equal to the total height of the page, it means that it has been scrolled to the bottom.

When scrolling to the bottom, we can load more content. In this example, we will demonstrate using simulated data to focus on key technologies. In actual projects, you need to make corresponding modifications according to the needs and data interface of your own project.

window.addEventListener('scroll', function() {
  var windowHeight = window.innerHeight; // 可见窗口的高度
  var fullHeight = document.body.clientHeight; // 页面的总高度
  var scrollTop = window.scrollY; // 页面滚动的垂直距离

  if (scrollTop + windowHeight >= fullHeight) {
    // 加载更多内容的代码，以下为示例
    var newData = getMoreData(); // 模拟获取更多数据的函数
    var container = document.getElementById('container'); // 内容容器的 DOM 元素

    newData.forEach(function(item) {
      var img = document.createElement('img');
      img.src = item.src;
      img.onload = function() {
        // 图片加载完成后，计算该图片的缩放比例
        var ratio = Math.min(window.innerWidth / img.width, windowHeight / img.height);
        img.style.width = img.width * ratio + 'px';
        img.style.height = img.height * ratio + 'px';
        container.appendChild(img);
      };
    });
  }
});

function getMoreData() {
  // 模拟获取更多数据的函数，返回一个包含图片信息的数组
  return [
    { src: 'image1.jpg' },
    { src: 'image2.jpg' },
    { src: 'image3.jpg' },
    // ...
  ];
}

In the above sample code, we determine whether to scroll to the bottom of the page in the callback function of the scroll event. If so, call the getMoreData() function to simulate the operation of obtaining more data, and calculate the scaling ratio for each image to maintain the aspect ratio. The scaling effect is achieved by adjusting the width and height styles of the IMG element.

It should be noted that we can only obtain the original width and height of the image after the image is loaded, so before the image is loaded, we first create a temporary IMG element, and Set the src attribute. Then when the image is loaded, calculate the scaling and set the width and height styles, and finally add the image to the container.

The above is a sample code that uses JavaScript to automatically load content while maintaining the aspect ratio when scrolling to the bottom of the page. You can modify and expand the code accordingly according to actual needs. Hope this article is helpful to you!

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