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.

+ add another resource

JavaScript

Babel is required to process package imports. If you need a different preprocessor remove all packages first.

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

Behavior

Save Automatically?

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

              
                <main>
  <h2>Using the <code>WheelEvent</code> Interface</h2>
  
  <p>In addition to traditional mouse events like click and scroll, you can also detect mouse wheel events and get some info from the <code>event</code> object.</p>
  
  <p>Try scrolling your mouse wheel up or down. The page will display info about the wheel event. You can also hold the SHIFT key while moving the mouse wheel to move horizontally (left/right) instead of vertically (up/down).</p>
  
  <output>[Scroll your mouse wheel]</output>
  
</main>
              
            
!

CSS

              
                body {
  font-family: Arial, sans-serif;
  font-size: 20px;
  padding: 0 20px;
  width: 3000px;
  height: 2000px;
}

main {
  max-width: 800px;
}

p {
  text-align: left;
  padding: 0 20px;
}

code {
  color: firebrick;
}

output {
  position: fixed;
  border: solid 1px #ccc;
  padding: 14px;
}
              
            
!

JS

              
                let op = document.querySelector('output'),
    msg;

document.addEventListener('wheel', function (e) {
  
  if (e.deltaY > 0) {
    msg = `You scrolled vertically down the page ${e.deltaY}px`;
    console.log(e.deltaMode);
  } else {
    msg = `You scrolled vertically up the page ${Math.abs(e.deltaY)}px`;
  }

  op.innerHTML = msg;
}, false);
              
            
!
999px

Console