Hot Module Replacement

The template project contains files necessary to utilize 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 allows you to retain the state of the application, too.

Main.kt

package com.example

import pl.treksoft.kvision.hmr.ApplicationBase
import pl.treksoft.kvision.hmr.module
import kotlin.browser.document

fun main(args: Array<String>) {
    var application: ApplicationBase? = null

    val state: dynamic = module.hot?.let { hot ->
        hot.accept()

        hot.dispose { data ->
            data.appState = application?.dispose()
            application = null
        }

        hot.data
    }

    if (document.body != null) {
        application = start(state)
    } else {
        application = null
        document.addEventListener("DOMContentLoaded", { application = start(state) })
    }
}

fun start(state: dynamic): ApplicationBase? {
    if (document.getElementById("kvapp") == null) return null
    @Suppress("UnsafeCastFromDynamic")
    App.start(state?.appState ?: emptyMap())
    return App
}

The main KVision application class is defined as an object extending ApplicationBase class.

App.kt

package com.example

import pl.treksoft.kvision.hmr.ApplicationBase
import pl.treksoft.kvision.panel.Root
import pl.treksoft.kvision.require

object App : ApplicationBase {

    private lateinit var root: Root

    override fun start(state: Map<String, Any>) {
        root = Root("kvapp") {
            // TODO
        }
    }

    override fun dispose(): Map<String, Any> {
        root.dispose()
        return mapOf()
    }

}

The HMR module calls 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 Map<String, Any> from thedispose method. It will be sent back to the application in the state parameter of the start method.