**Run in browser:** `./gradlew jsRun` ### How to use HTML based @Composable functions in JS? Useful links: - [Use Kotlin Code from JS](https://kotlinlang.org/docs/js-to-kotlin-interop.html) - [JavaScript modules](https://kotlinlang.org/docs/js-modules.html) - [webpack bundling](https://kotlinlang.org/docs/js-project-setup.html#webpack-bundling) 1) @Composable functions can't be invoked from JS directly (because every @Composable function has implicit parameters added by compiler plugin) 2) We can wrap @Composable functions into some usual function (with [@JsExport](https://kotlinlang.org/docs/js-to-kotlin-interop.html#jsexport-annotation)) which can be invoked in JS as is. 3) Every call to a "wrapping" function will create a composition (part of DOM controlled by Compose runtime) 4) It's important to `dispose` a composition when it's not needed. 5) The composition's state can be controlled by creating an arbitrary `Controller` class, which implements and exposes necessary functions for state updates. ### Simplified example (see full example in `src/jsMain`): ```kotlin // Composables.kt @JsExport abstract class ComposeCounterAppController { abstract fun setCount(newCount: Int) abstract fun dispose() } @JsExport fun ComposeCounterApp(rootId: String, onCountChange: (Int) -> Unit = {}): ComposeCounterAppController { var count: Int by mutableStateOf(0) val composition = renderComposable(rootElementId = rootId) { // Counter is a @Composable function // see full example in src/jsMain Counter(count) { count = it onCountChange(count) } } return object : ComposeCounterAppController() { override fun setCount(newCount: Int) { count = newCount } override fun dispose() { composition.dispose() } } } ``` Then in JS we can use `ComposeCounterApp` function: ```javascript // see src/jsMain/resources/use_compose.js file for a full example counterController = MyComposables.ComposeCounterApp('counterByCompose', (newCount) => { console.log(`Counter was updated. New value = ${newCount}`); }); ``` The module name was overridden to make it convenient for usage in JS: ``` // webpack.config.d/configModuleName.js config.output = config.output || {}; config.output.library = "MyComposables"; ``` ### Building and using the output ``` ./gradlew jsBrowserProductionWebpack ``` This will produce the output in `build/distributions`. Then we can use exported functions from `web-compose-in-js.js` (the filename is defined by the project/module name). ```html ```