Hot Module Replacement

When developing with Js target you can use the HMR (Hot Module Replacement) feature of Webpack. HMR can significantly speed up development by updating browser content automatically after changes are made in the source code. It also allows you to retain the state of the application. Just override the start method with a state parameter.

main.kt

import dev.kilua.Application
import dev.kilua.Hot
import dev.kilua.compose.root
import dev.kilua.startApplication

class App : Application() {

    override fun start(state: String?) {
        root("root") {
            // TODO
        }
    }

    override fun dispose(): String? {
        return null
    }

}

fun main() {
    startApplication(::App, js("import.meta.webpackHot").unsafeCast<Hot?>())
}

The js("import.meta.webpackHot").unsafeCast<Hot?>() call is JS target specific and can't be used in the common code. Declare a simple expect/actual function expect fun webpackHot(): Hot? if you want do use HMR with shared Js/WasmJs sources sets.

The HMR module calls the start method after every change in the source code, and this method is responsible for recreating the user interface.

In case of a need to retain the state of the application, it should be returned as a String (e.g. serialized json) from thedispose method. It will be sent back to the application in the state parameter of the start method.