Pen Settings

HTML

CSS

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

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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.

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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.

Behavior

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Auto-Updating Preview

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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

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HTML

              
                <h1><a href="index.html">WEB</a></h1>
  <input type="button" value="night" onclick="
    document.querySelector('body').style.backgroundColor = 'black';
    document.querySelector('body').style.color = 'white';
  ">
  <input type="button" value="day" onclick="
    document.querySelector('body').style.backgroundColor = 'white';
    document.querySelector('body').style.color = 'black';
  ">
  <ol>
    <li><a href="1.html">HTML</a></li>
    <li><a href="2.html">CSS</a></li>
    <li><a href="3.html">JavaScript</a></li>
  </ol>
  <h2>JavaScript</h2>
  <p>
    JavaScript (/ˈdʒɑːvəˌskrɪpt/[6]), often abbreviated as JS, is a high-level, dynamic, weakly typed, prototype-based, multi-paradigm, and interpreted programming language. Alongside HTML and CSS, JavaScript is one of the three core technologies of World Wide Web content production. It is used to make webpages interactive and provide online programs, including video games. The majority of websites employ it, and all modern web browsers support it without the need for plug-ins by means of a built-in JavaScript engine. Each of the many JavaScript engines represent a different implementation of JavaScript, all based on the ECMAScript specification, with some engines not supporting the spec fully, and with many engines supporting additional features beyond ECMA.
  </p>
              
            
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Console