<code-sample>

A wrapper element for highlight.js

A themeable sample code snippet that uses highlight.js for syntax highlighting. Forget to worry about spaces, indentation, HTML entities, etc.

<code-sample>
  <template>
    <div class="some-class">
      <p>Lorem ipsum dolor…</p>
    </div>
  </template>
</code-sample>

Installation

Install the component using Npm:

$ npm i -S @kuscamara/code-sample highlight.js

Import Web Components loader (optional):

<script src="node_modules/@webcomponents/webcomponentsjs/webcomponents-loader.js"></script>

Import the component:

<script type="module" src="node_modules/highlight.js/lib/index.js"></script>
<script type="module" src="node_modules/@kuscamara/code-sample/code-sample.js"></script>

Usage

The code to highlight must be provided inside a <template> tag.

<code-sample>
  <template>
    <p>your code here...</p>
  </template>
</code-sample>

Used inside a custom element

When used inside a custom element you'll need to add the attribute preserve-content to the inner template to prevent Polymer to process the template's content.

<code-sample>
  <template preserve-content>
    <p>your code here...</p>
  </template>
</code-sample>

Used inside a tagged template literal

When used inside a tagged template literal (Polymer or LitElement html function), you should escape any template string (${expression}) to prevent it from being evaluated getting an error.

class SomeElement extends PolymerElement {
  static get template() {
    return html`
      <code-sample type="js">
        <template preserve-content>
          export class Example extends ExampleBase {
            static get template() {
              return html\`
                <p>\${super.template}</p>
              \`;
            }
          }
        </template>
      </code-sample>
    `;
  }
}

Render the code inside the template

To render the code inside the template, use the boolean attribute render.

<code-sample render>
  <template>
    <my-custom-element></my-custom-element>
  </template>
</code-sample>

Copy to clipboard

To display a copy to clipboard button, use the boolean attribute copy-clipboard-button:

<code-sample copy-clipboard-button>
  <template>
    <p>your code here...</p>
  </template>
</code-sample>

Language types

The type attribute specifies the language of the sample code (eg.: html, css, js) and is not needed most of the time because it's automatically set. You can use it when your code sample language is not properly detected.

<code-sample type="css">
  <template>
    .some-class {
      @apply --my-mixin;
    }
  </template>
</code-sample>

Exception: for the case of tagged template literals, you may need to set the type attribute to js, jsx or javascript to prevent the code being formatted as HTML.

<code-sample type="js">
  <template>
    class MyElement extends PolymerElement {
      static get template() {
        return html`
          <style>
            :host {
              display: block;
            }
          </style>
          <p>Hello world!</p>
        `;
      }
    }
  </template>
</code-sample>

Themes

The component includes 8 themes. One Dark is imported as the default theme. To use another theme, import it and set as the theme property.

Example:

<script type="module">
  import { oneLight } from '../node_modules/@kuscamara/code-sample/themes/one-light.js';
  document.querySelector('code-sample').theme = oneLight;
</script>

Available themes

one-ligth.js as oneLight
default.js as defaultTheme
github.js as github
one-dark.js as oneDark
solarized-dark.js as solarizedDark
solarized-light.js as solarizedLight
kustom-light.js as kustomLight
kustom-dark.js as kustomDark

More themes

You can use your own theme by adding one of the available themes for hightlight.js in a shared style. The shared style should be exported as a tagged template literal.

Example:

import { html } from '@polymer/polymer/polymer-element.js';

export const myOwnTheme = html`
<style>
/* your own styles */
</style>`;

Themes in browsers using ShadyCSS

Due to ShadyCSS limitations, dynamic change of themes is not supported in browsers that use ShadyCSS (Firefox). To set a different theme for these browsers, you should import your theme as a style module with code-sample-theme as its id.

Example:

In your-shared-style-file.js:

const html = (string) => string;
const $documentContainer = document.createElement('div');
$documentContainer.setAttribute('style', 'display: none;');

$documentContainer.innerHTML = html`
<dom-module id="code-sample-theme">
  <template>
    <style>
    /* your custom styles */
    </style>
  </template>
</dom-module>`;

document.head.appendChild($documentContainer);

Import the shared style in the main document:

<head>
  <script type="module" src="your-shared-style-file.js"></script>
</head>

The styles will be applied to <code-sample> in browsers using ShadyCSS.

Languages included in the highlightjs pack included with the component:

CSS
HTTP
JavaScript
Bash
CoffeScript
JSON
Markdown
HTML, XML

highlightjs version: v9.12.0

Styling

The following custom CSS properties are available for styling:

Custom Property	Description	Default
--code-sample-pre	empty mixin applied to `<pre>` element	{}
--code-sample-font-family	font-family applied to `<pre>` and `<code>` elements	Operator Mono, Inconsolata, Roboto Mono, monaco, consolas, monospace
--code-sample-font-size	font-size applied to `<pre>` and `<code>` elements	14px
--code-sample-line-height	line-height applied to `.hljs`	1.3
--code-sample-hljs	empty mixin applied to `.hljs`	{}
--code-sample-demo-padding	padding applied to the container of the rendered code	0 0 20px
--code-sample-demo-not-empty	empty mixin applied to the demo container when is not empty	{}
--code-sample-demo	empty mixin applied to the container of the rendered code	{}
--code-sample-code-container	empty mixin applied to code container	{}
--code-sample-code-container-hover	empty mixin applied to code container on :hover	{}
--code-sample-code-container-hover-button	empty mixin applied to the copy to clipboard button when the code container on :hover	{}
--code-sample-copy-button-bg-color	background-color of the copy to clipboard button	#e0e0e0
--code-sample-copy-clipboard-button	empty mixin applied to the copy to clipboard button	{}

Included themes contain custom CSS properties to set the background and text color. You may need to add these CSS properties to your own themes.

Custom property	Description	Default
--code-sample-background	code background color	Depends on the theme
--code-sample-color	code text color	Depends on the theme

d4l3k/code-sample