Pen Settings

HTML

CSS

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URLs added here will be added as <link>s in order, and before the CSS in the editor. You can use the CSS from another Pen by using its URL and the proper URL extension.

+ add another resource

JavaScript

Babel includes JSX processing.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource

Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

Behavior

Auto Save

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.

HTML

              
                <div id="masonry" style="display: grid; place-items: center">
  <h1 style="height: 50vh">IntersectionObserver</h1>
  <h1 style="height: 50vh">向下滚动</h1>
</div>
<div id="masonryFooter">到底了~</div>
              
            
!

CSS

              
                
              
            
!

JS

              
                // 无限滚动
// 这个例子的缺点是,如果底部元素一开始就是可见的,那么不会触发回调函数
// 只有从不可见变为可见时,才触发加载
const io = new IntersectionObserver((entries) => {
  entries.forEach((entry) => {
    // 不可见时,返回
    if (entry.intersectionRatio === 0) return;
    // 如果瀑布流的底部可见,则触发加载
    loadItem();
  });
});

io.observe(document.querySelector("#masonryFooter"));

let counter = 0;
function loadItem() {
  if (counter > 10) return;
  const h1 = document.createElement("h1");
  h1.innerHTML = ++counter;
  document.querySelector("#masonry").appendChild(h1);
}

              
            
!
999px

Console