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HTML

About HTML Preprocessors

HTML preprocessors can make writing HTML more powerful or convenient. For instance, Markdown is designed to be easier to write and read for text documents and you could write a loop in Pug.

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Adding Classes

In CodePen, whatever you write in the HTML editor is what goes within the <body> tags in a basic HTML5 template. So you don't have access to higher-up elements like the <html> tag. If you want to add classes there that can affect the whole document, this is the place to do it.

About the <head>

In CodePen, whatever you write in the HTML editor is what goes within the <body> tags in a basic HTML5 template. If you need things in the <head> of the document, put that code here.

!
Insecure Resource

The resource you are linking to is using the 'http' protocol, which may not work when the browser is using https.

CSS

About CSS Preprocessors

CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.

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CSS Base

About CSS Base

It's a common practice to apply CSS to a page that styles elements such that they are consistent across all browsers. We offer two of the most popular choices: normalize.css and a reset. Or, choose Neither and nothing will be applied.

Vendor Prefixing

About Vendor Prefixing

To get the best cross-browser support, it is a common practice to apply vendor prefixes to CSS properties and values that require them to work. For instance -webkit- or -moz-.

We offer two popular choices: Autoprefixer (which processes your CSS server-side) and -prefix-free (which applies prefixes via a script, client-side).

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.

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About External Resources

You can apply CSS to your Pen from any stylesheet on the web. Just put a URL to it here and we'll apply it, in the order you have them, before the CSS in the Pen itself.

You can also link to another Pen here (use the .css URL Extension) and we'll pull the CSS from that Pen and include it. If it's using a matching preprocessor, use the appropriate URL Extension and we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.

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JavaScript

About JavaScript Preprocessors

JavaScript preprocessors can help make authoring JavaScript easier and more convenient.

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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.

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About External Resources

You can apply a script from anywhere on the web to your Pen. Just put a URL to it here and we'll add it, in the order you have them, before the JavaScript in the Pen itself.

If the script you link to has the file extension of a preprocessor, we'll attempt to process it before applying.

You can also link to another Pen here, and we'll pull the JavaScript from that Pen and include it. If it's using a matching preprocessor, we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.

Learn more

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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.

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About Packages

Using packages here is powered by esm.sh, which makes packages from npm not only available on a CDN, but prepares them for native JavaScript ESM usage.

All packages are different, so refer to their docs for how they work.

If you're using React / ReactDOM, make sure to turn on Babel for the JSX processing.

Behavior

Auto Save

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Format on Save

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HTML 

              
                <h1>Infinite Scroll v4 - elementScroll: true, vanilla JS</h1>

<div class="container">
  <article class="post">
    <h1>1a - Lorem ipsum dolor sit amet</h1>
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc tristique mauris nec sapien efficitur, sit amet varius est interdum. Curabitur quis sem felis. Curabitur at quam sit amet mi tempor tristique quis in lorem. Cras id felis sit amet erat accumsan ornare.</p>
    <p><img src="https://s3-us-west-2.amazonaws.com/s.cdpn.io/82/orange-tree.jpg" alt="orange-tree" /></p>
    <p>Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos.</p>
    <p>Nullam vel odio nec turpis consequat iaculis at ut nibh. Nulla interdum lacus vitae sapien porttitor congue sagittis ac felis.Curabitur in ligula porttitor, varius purus sed, elementum nibh. Nunc ut libero posuere.</p>
  </article>
  <article class="post">
    <h1>1b - Ullamcorper quam at</h1>
    <p>Ullamcorper quam at, hendrerit eros. Mauris quis vehicula enim.</p>
    <p><img src="https://s3-us-west-2.amazonaws.com/s.cdpn.io/82/cat-nose.jpg" alt="cat nose"></p>
    <p>Duis elementum nisi tortor, ut elementum quam mattis condimentum. Aenean vitae massa sit amet ligula sollicitudin venenatis. Praesent ultrices laoreet hendrerit. Duis tempus ullamcorper enim, ac volutpat augue faucibus sit amet.</p>
    <p>Donec at consequat elit. Suspendisse dignissim ante vitae urna rutrum cursus. Morbi finibus semper facilisis. In varius sem ut turpis molestie volutpat. Duis ut posuere est. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Duis malesuada placerat luctus. In eget feugiat sapien. Sed gravida ultrices accumsan.</p>
    <p>In nec ex at mi scelerisque malesuada.</p>
    <p>Nullam arcu diam, mollis sit amet condimentum et, finibus in ex. Morbi bibendum magna vel tortor fringilla efficitur. Aliquam sed lectus lacus.</p>
  </article>
  <article class="post">
    <h1>1c - Orci varius natoque penatibus et magnis dis parturient montes</h1>
    <p>Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. In varius turpis ipsum, et porta eros eleifend ullamcorper. Sed arcu nisl, rhoncus porta fermentum in, eleifend non dolor.</p>
    <p>Mauris sagittis a lectus eu fringilla. Maecenas varius cursus aliquam.</p>
    <p>Suspendisse maximus congue augue eu venenatis. Aliquam urna purus, suscipit ut purus vel, iaculis rhoncus nulla. Donec a velit elementum, pellentesque metus blandit, lacinia erat. Fusce pulvinar mattis erat ac efficitur. Pellentesque aliquam eleifend ligula, eu ullamcorper elit pretium sit amet.</p>
    <p>Praesent placerat eros sem, vel pretium libero pharetra nec. Morbi hendrerit eleifend commodo. Morbi sodales nunc purus, consequat eleifend nulla dignissim non.</p>
  </article>
  <article class="post">
    <h1>1d - Donec a urna in turpis maximus</h1>
    <p>Donec a urna in turpis maximus faucibus a nec mauris.</p>
    <p>Donec iaculis, justo a egestas venenatis, dui nisl faucibus urna, sit amet condimentum quam dui ut libero. Etiam aliquet urna quis nisi aliquam, vitae tincidunt est feugiat.</p>
    <p>Integer viverra at arcu quis faucibus. Praesent nec venenatis odio. Donec non mattis massa, quis vestibulum leo. Etiam eleifend diam ac magna egestas aliquam. Sed vulputate risus eget efficitur auctor. Mauris aliquam ac purus at semper. Praesent vulputate hendrerit eros, vitae semper turpis venenatis et. Proin et est felis. Etiam sem risus, elementum id cursus quis, laoreet quis orci. Cras eget fermentum lorem, vitae pharetra augue. Etiam tincidunt nulla faucibus, egestas lacus sed, semper metus.</p>
  </article>
</div>
!

CSS 

              
                body {
  font-family: sans-serif;
  line-height: 1.4;
  font-size: 18px;
  padding: 20px;
  max-width: 640px;
  margin: 0 auto;
}

.container {
  padding: 10px;
  border: 1px solid #DDD;
  height: 400px;
  overflow-y: scroll;
}

.post {
  border-top: 1px solid #DDD;
  margin: 60px 0;
}

.post img {
  display: block;
  max-width: 100%;
}
!

JS 

              
                //-------------------------------------//
// init Infinte Scroll

let infScroll = new InfiniteScroll( '.container', {
  path: getPenPath,
  append: '.post',
  elementScroll: true,
});

//-------------------------------------//
// hack CodePen to load pens as pages

function getPenPath() {
  const nextPenSlugs = [
    '3d9a3b8092ebcf9bc4a72672b81df1ac',
    '2cde50c59ea73c47aec5bd26343ce287',
    'd83110c5f71ea23ba5800b6b1a4a95c4',
  ];

  let slug = nextPenSlugs[ this.loadCount ];
  if ( slug ) return `/desandro/debug/${slug}`;
}
!
999px

Console