code-pen

A Web Component for opening code blocks in CodePen.

Demo | Attributes demo | Further reading

Examples

General usage example:

<script type="module" src="code-pen.js"></script>

<code-pen>
  <pre>
    <code>&lt;p&gt;Hello world&lt;/p&gt;</code>
  </pre>
</code-pen>

Note that the code samples have been escaped so they can be seen on the page correctly

Examlpe with 3 code elements which default to HTML, CSS and JavaScript respectively:

<script type="module" src="code-pen.js"></script>

<code-pen>
  <pre>
    <code>&lt;p&gt;Hello world&lt;/p&gt;</code>
  </pre>
  <pre>
    <code>:root { color: hotpink; }</code>
  </pre>
  <pre>
    <code>document.querySelector(&quot;p&quot;).style.backgroundColor = &quot;orange&quot;;</code>
  </pre>
</code-pen>

Features

This Web Component allows you to:

• Open code samples in the CodePen editor without any configuration
  • Open a single HTML code sample
  • Open a pair of HTML and CSS code samples, in respective order
  • Open a trio of HTML, CSS and JavaScript code samples, in respective order
• Adjust where the code sample is filled into in CodePen using the css and js attributes (html is the default)
• Adjust which elements are used as the code sample source by using the html, css and js attributes and an element selector as its value (e.g. css="textarea")
• Add a title to the pre-filled pen using the title attribute
• Change the "Open in CodePen" button text label using the label attribute 
• Allow readers to edit the code before opening in CodePen using contenteditable on the code container
• Use a custom template for specific instances using the template attribute

Installation

You have a few options (choose one of these):

1. Install via npm: npm install @daviddarnes/code-pen
2. Download the source manually from GitHub into your project.
3. Skip this step and use the script directly via a 3rd party CDN (not recommended for production use)

Usage

Make sure you include the <script> in your project (choose one of these):

<!-- Host yourself -->
<script type="module" src="code-pen.js"></script>

<!-- 3rd party CDN, not recommended for production use -->
<script
  type="module"
  src="https://www.unpkg.com/@daviddarnes/[email protected]/code-pen.js"
></script>

<!-- 3rd party CDN, not recommended for production use -->
<script type="module" src="https://esm.sh/@daviddarnes/[email protected]"></script>

Using attributes

By default the <code-pen> component will assume the first code element it finds goes into the HTML editor in CodePen, the second goes into the CSS editor, and JavaScript into the third. If there is only one or two code elements it'll still follow this order and leave the missing ones blank in CodePen. However with attributes the order can be modified and changed.

Applying the css or js attributes will cause a single code elements content to be insered into the CSS or JavaScript editors in CodePen respectively:

<script type="module" src="code-pen.js"></script>

<code-pen css>
  <pre>
    <code>:root { background: hotpink; }</code>
  </pre>
</code-pen>

<script type="module" src="code-pen.js"></script>

<code-pen js>
  <pre>
    <code>document.body.style.backgroundColor = &quot;orange&quot;;</code>
  </pre>
</code-pen>

Note that, as mentioned above, not applying any attributes will mean the single code elements content will be inserted into the HTML editor on CodePen

You can also overwrite the element selection entirely using the html, css and js attributues to set an element selector for each piece of code. This is useful for cases where your code is out of order, you have extra rogue elements in your content or if you wish to use a different element entirely.

<script type="module" src="code-pen.js"></script>

<code-pen html=".language-html" css=".language-css" js=".language-js">
  <pre>
    <code>I'm a rogue code block to ruin this Web Component demo</code>
  </pre>
  <pre>
    <code class="language-js">document.querySelector(&quot;p&quot;).style.backgroundColor = &quot;orange&quot;;</code>
  </pre>
  <pre>
    <code class="language-html">&lt;p&gt;Hello world&lt;/p&gt;</code>
  </pre>
  <pre>
    <code class="language-css">:root { color: hotpink; }</code>
  </pre>
</code-pen>

<script type="module" src="code-pen.js"></script>

<code-pen css="textarea">
  <textarea>:root { background: hotpink; }</textarea>
</code-pen>

Optionally you can set the title of the newly create pen in CodePen as well as the button label for the "Open in CodePen" button using title and label respectively:

<script type="module" src="code-pen.js"></script>

<code-pen title="Hello world example" label="Create new pen">
  <pre>
    <code>&lt;p&gt;Hello world&lt;/p&gt;</code>
  </pre>
</code-pen>

The component also works if you want readers to be able to edit the code before opening it in CodePen. Either use a textarea or input element to contain the code samples, or add a contenteditable="true" attribute to the immediate containing element:

<script type="module" src="code-pen.js"></script>

<code-pen>
  <pre>
    <code contenteditable="true">&lt;p&gt;Hello world&lt;/p&gt;</code>
  </pre>
</code-pen>

Using a custom template

The default template for the component looks like this:

<form action="https://codepen.io/pen/define" method="POST" target="_blank">
  <input type="hidden" name="data">
  <input type="submit" value="Open in CodePen">
</form>

However you can customise the template by using a element with an id of code-pen-template, which will be used for every instance of the component on the page:

<template id="code-pen-template">
  <form action="https://codepen.io/pen/define" method="POST" target="_blank">
    <input type="hidden" name="data">
    <button>Open in CodePen</button>
  </form>
</template>

If you do create a custom template it must:

1. Use a form element which has the correct attributes to submit it to CodePen's API
2. Have a hidden input with a name attribute called data, this is for both CodePen and for the component
3. Some form of UI to submit the form

Note that when you do create a custom template you automatically opt out of using the label attribute option

Credit

With thanks to the following people:

• Zach Leatherman for inspiring this Web Component repo template