Self-contained component to embed in websites for running Kotlin, Arrow library aware, code

Usage no npm install needed!

<script type="module">
  import arrowPlayground from '';


NPM version

Arrow Playground

Component that creates Kotlin-aware, including the Arrow library, editors capable of running code from HTML block elements. This is a fork of the original Kotlin Playground work done by JetBrains team.


Arrow Playground preview


Load it from a CDN

Generate the library through the proper npm script, then host it and insert a <script> element into your page, specifying what elements should be converted in its data-selector attribute.

<script src="" data-selector="code"></script>

Or, if you need to separate process of loading/conversion, omit the data-selector attribute and use a second <script> element like this:

<script src=""></script>

document.addEventListener('DOMContentLoaded', function() {

It's necessary to set the server where the code will be sent to be compiled and run with the Arrow libraries. For that you can set the data-server attribute:

<script src=""

The custom playground server comes from kotlin-compiler-server.

Host your own instance

Install arrow-playground as dependency via NPM.

npm install arrow-playground -S

And then just use it in your code.

// ES5
var playground = require('arrow-playground');

document.addEventListener('DOMContentLoaded', function() {
  playground('code'); // attach to all <code> elements

// ES6
import playground from 'arrow-playground';

document.addEventListener('DOMContentLoaded', () => {
  playground('code'); // attach to all <code> elements

Use from plugins

  1. Kotlin Playground WordPress pluginWordPress plugin which allows to embed interactive Kotlin playground to any post.
  2. Kotlin Playground Coursera plugin — Allows embedding interactive Kotlin playground for coursera lessons.
  3. Kotlin Playground Orchid plugin — Allows embedding interactive Kotlin playground in Orchid documentation sites.


Kotlin Playground supports several events, and also Kotlin version or server URL overwriting passing an additional options parameter on initialisation.

For example:

function onChange(code) {
  console.log("Editor code was changed:\n" + code);

function onTestPassed() {
   console.log("Tests passed!");

const options = {
  server: 'https://my-arrow-playground-server',
  onChange: onChange,
  onTestPassed: onTestPassed,
  callback: callback(targetNode, mountNode)

playground('.selector', options)

Events description:

  • onChange(code) — Fires every time the content of the editor is changed. Debounce time: 0.5s. code — current playground code.

  • onTestPassed — Is called after all tests passed. Use for target platform junit.

  • onTestFailed — Is called after all tests failed. Use for target platform junit.

  • onCloseConsole — Is called after the console's closed.

  • onOpenConsole — Is called after the console's opened.

  • getJsCode(code) — Is called after compilation Kotlin to JS. Use for target platform js. code — converted JS code from Kotlin.

  • callback(targetNode, mountNode) — Is called after playground's united. targetNode — node with plain text before component initialization. mountNode — new node with runnable editor.

  • getInstance(instance) - Getting playground state API.

    instance.state      // playground attributes, dependencies and etc.
    instance.nodes      // playground NodeElement.
    instance.codemirror // editor specification.
    instance.execute()  // function for executing code snippet.
    instance.getCode()  // function for getting code from snippet.

Customizing editors

Use the following attributes on elements that are converted to editors to adjust their behavior.

  • args: Command line arguments.

    <code args="1 2 3">
    Your code here
  • auto-indent="true|false": Whether to use the context-sensitive indentation. Defaults to false.

  • theme="idea|darcula|default": Editor IntelliJ IDEA themes.

  • mode="kotlin|js|java|groovy|xml|c|shell|swift|obj-c": Different languages styles. Runnable snippets only with kotlin. Default to kotlin.

  • indent="4": How many spaces a block should be indented. Defaults to 4.

  • lines="true|false": Whether to show line numbers to the left of the editor. Defaults to false.

  • from="5" to="10: Create a part of code. Example from line 5 to line 10.

  • data-output-height="200": Set the iframe height in px in output. Use for target platform canvas.

  • match-brackets="true|false"": Determines whether brackets are matched whenever the cursor is moved next to a bracket. Defaults to false.

Supported keyboard shortcuts

  • Ctrl+Space— code completion
  • Ctrl+F9/Cmd+R— execute snippet
  • Ctrl+/— comment code
  • Ctrl+Alt+L/Cmd+Alt+L — format code
  • Shift+Tab— decrease indent

Develop and contribute

  1. Install required dependencies yarn install.
  2. yarn start to start local development server at http://localhost:9000.
  3. yarn run build to create production bundles.