Pen Settings

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

You're using npm packages, so we've auto-selected Babel for you here, which we require to process imports and make it all work. If you need to use a different JavaScript preprocessor, remove the packages in the npm tab.

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

Use npm Packages

We can make npm packages available for you to use in your JavaScript. We use webpack to prepare them and make them available to import. We'll also process your JavaScript with Babel.

⚠️ This feature can only be used by logged in users.

Code Indentation


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.

HTML Settings

Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

  <div id="pulse_text" class="text">click to play</div>
  <div id="pulse" class="box">pulse</div>
  <div id="bounce_text" class="text">click to play</div>
  <div id="bounce" class="box">bounce</div>
              @import url('https://fonts.googleapis.com/css?family=Luckiest+Guy');

html {
  box-sizing: border-box;
  font-family: -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Oxygen-Sans,Ubuntu,Cantarell,"Helvetica Neue",sans-serif;
*, *:before, *:after {
  box-sizing: inherit;
body {
  margin: 0;
  padding: 0;

main {
  align-items: center;
  background-color: #1d1e22;
  display: flex;
  flex-direction: column;
  height: 100vh;
  width: 100vw;

.text {
  color: #E0E0E0;
  font-size: 16px;
  margin: 30px 0 10px;
  padding: 5px 40px;

#pulse {
  animation-iteration-count: 3;

.box {
  align-items: center;
  background-color: #fff;
  border: 4px solid rebeccapurple;
  color: rebeccapurple;
  cursor: pointer;
  display: flex;
  font-family: 'Luckiest Guy';
  font-size: 40px;
  height: 60px;
  justify-content: center;
  width: 400px;
  will-change: transform;
              // our elements
var pulseText = document.querySelector('#pulse_text');
var pulse = document.querySelector('#pulse');
var bounceText = document.querySelector('#bounce_text');
var bounce = document.querySelector('#bounce');

// function for playing our pulse animation
function playPulse () {
	// prevent extra clicks during animation
  pulse.removeEventListener('click', playPulse);
  // add the library's classes
  pulse.classList.add('animated', 'pulse');
  // hide the play text since we can't click during animation
  pulseText.style.opacity = 0;
// event listener calls a function so we can prevent extra clicks
pulse.addEventListener('click', playPulse);
// function to reset after animation ends
pulse.addEventListener('animationend', function () {
	// restore event listener
	pulse.addEventListener('click', playPulse);
  // remove library's classes so they can be placed again
  pulse.classList.remove('animated', 'pulse');
  // restore the text since we can now click again
  pulseText.style.opacity = 1;

// function to play our infinite bounce animation
bounce.addEventListener('click', function () {
	// check to see if library classes have been applied
	if (!bounce.classList.contains('animated')) {
  	// animation is not playing, we will start it
    // change text to explain how to stop animation
  	bounceText.innerText = 'click to stop';
    // add the library's classes
  	bounce.classList.add('animated', 'bounce', 'infinite');
  } else {
  	// animation is playing, we will stop it
    // change text to explain how to start animation
  	bounceText.innerText = 'click to play';
    // remove the library's classes
  	bounce.classList.remove('animated', 'bounce', 'infinite');
🕑 One or more of the npm packages you are using needs to be built. You're the first person to ever need it! We're building it right now and your preview will start updating again when it's ready.