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official JetBrains project NPM version

Kotlin Playground

Component that creates Kotlin-aware editors capable of running code from HTML block elements.



Use our CDN

Insert a <script> element into your page and specify 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() {

You can also overwrite the server where the code will be sent to be compiled and analyzed (for example if you host a server instance that includes your own Kotlin libraries). For that you can set the data-server attribute.

And you can also set a default Kotlin version for code snippets to run on. Bear in mind that the version set per editor will take precedence though:

<script src=""

Fork & clone the old server repository or the new server.

Host your own instance

Install Kotlin-playground as dependency via NPM.

npm install kotlin-playground -S

And then just use it in your code.

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

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

// ES6
import playground from 'kotlin-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-kotlin-playground-server',
  version: '1.3.50',
  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.

  • data-version: Target Kotlin compiler version:

     <code data-version="1.0.7">
     Your code here
  • args: Command line arguments.

    <code args="1 2 3">
    Your code here
  • data-target-platform: target platform: junit, canvas, js or java (default).

     <code data-target-platform="js">
      Your code here
  • data-highlight-only: Read-only mode, with only highlighting. data-highlight-only="nocursor" - no focus on editor.

    <code data-highlight-only>
      Your code here

    Or, you can make only a part of code read-only by placing it between //sampleStart and //sampleEnd markers. If you don't need this just use attribute none-markers. For adding hidden files: put files between <textarea> tag with class hidden-dependency.

    import cat.Cat
    fun main(args: Array<String>) {
        val cat = Cat("Kitty")
      <textarea class="hidden-dependency">
        package cat
        class Cat(val name: String)

    Also if you want to hide code snippet just set the attribute folded-button to false value.

  • data-js-libs: By default component loads jQuery and makes it available to the code running in the editor. If you need any additional JS libraries, specify them as comma-separated list in this attribute.

    <code data-js-libs="https://my-awesome-js-lib/lib.min.js">
      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.

  • data-min-compiler-version="1.0.7": Minimum target Kotlin compiler version

  • data-autocomplete="true|false": Get completion on every key press. If false => Press ctrl-space to activate autocompletion. Defaults to false.

  • highlight-on-fly="true|false": Errors and warnings check for each change in the editor. Defaults to false.

  • 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

  • data-crosslink="enabled|disabled": Show link for open in playground. Defaults to undefined – only supported in playground.

  • data-shorter-height="100": show expander if height more than value of attribute

  • data-scrollbar-style: Chooses a scrollbar implementation. Defaults to overlay.

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
  • Ctrl+Alt+H/Cmd+Alt+H — highlight code
  • Ctrl+Alt+Enter/Cmd+Alt+Enter — show import suggestions

Develop and contribute

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