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1.19.0 • Public • Published

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 attibute, like this:

<script src=""

Fork & clone server repository.

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.


Kotlin Playground supports several events, and also 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',
  onChange: onChange(code),
  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.

  • 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.

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. Fork & clone our repository.
  2. Install required dependencies npm install.
  3. npm start to start local development server at http://localhost:9000, or npm start -- --env.webDemoUrl=http://localhost:6666 if you want a different port.
  4. npm run build to create production bundles.


npm i kotlin-playground

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