The document discusses Kotlin's capabilities across various platforms including the JVM, JavaScript, and native platforms like iOS. It highlights Kotlin's ability to transpile to JavaScript to enable single page apps and IoT applications. It also demonstrates using Kotlin/JS to print to the browser console and integrating with JavaScript libraries and the DOM. Finally, it briefly mentions Kotlin Native for embedded systems and iOS and provides some example projects to try out Kotlin on different platforms.

1. Christopher Ng
Kotlinian @
Editor @ blacklenspub.com
Kotlin Wonderland

2. We love JVM

3. Single page app?
IoT?
TensorFlow?
iOS?

4. Let’s say goodbye
to JVM

5. Kotlin JavaScript

6. Kotlin.js
Main.jsMain.kt
Kotlin/JS

7. fun main(args: Array<String>) {
println("Hello JavaScript!")
}
var ConsoleOutput = function (Kotlin) {
'use strict';
var _ = Kotlin.defineRootPackage(null, {
main_kand9s$: function (args) {
Kotlin.println('Hello JavaScript!');
}
});
Kotlin.defineModule('ConsoleOutput', _);
_.main_kand9s$([]);
return _;
}(kotlin);
transpile

8. group 'com.babedev'
version '1.0-SNAPSHOT'
buildscript {
ext.kotlin_version = '1.1.4'
repositories {
mavenCentral()
}
dependencies {
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
}
}
apply plugin: 'kotlin2js'
repositories {
mavenCentral()
}
dependencies {
compile "org.jetbrains.kotlin:kotlin-stdlib-js:$kotlin_version"
}

9. compileKotlin2Js {
kotlinOptions.outputFile = "${projectDir}/web/output.js"
kotlinOptions.moduleKind = "commonjs"
}

10. build.doLast {
configurations.compile.each { File file ->
copy {
includeEmptyDirs = false
from zipTree(file.absolutePath)
into "${projectDir}/web"
include { fileTreeElement ->
def path = fileTreeElement.path
path.endsWith(".js") &&
(path.startsWith("META-INF/resources/") || !path.startsWith("META-INF/"))
}
}
}
}

11. JS Stdlib
- org.w3c.dom
- org.w3c.fetch
- org.w3c.xhr
- org.w3c.files
- org.w3c.notifications
- kotlin.js

12. org.w3c.dom
// Kotlin
val img = document.createElement("img")
img.setAttribute("src",
"https://kotlinlang.org/assets/images/open-graph/kotlin_250x250.png")
val div = document.getElementById("app")
div?.appendChild(img)
// Javascript
var img = document.createElement("img");
img.setAttribute("src",
"https://kotlinlang.org/assets/images/open-graph/kotlin_250x250.png");
var div = document.getElementById("app");
div != null ? div.appendChild(img) : null;

13. org.w3c.fetch
window.fetch("https://httpbin.org/ip")
.then({ response ->
response.json().then({ body ->
console.log(body)
})
})
.catch({ error ->
console.error(error.message)
})

14. Dynamic Type
val database = js("firebase.database()")!!
database.ref("/messages")
.on("value") { snapshot: dynamic ->
snapshot.forEach(fun (child: dynamic) {
console.log(child.`val()`)
})
}

15. External
// Javascript
function greet(msg) {
console.log(msg)
}
// Kotlin
external fun greet(msg: Any?): Unit
greet("Hello Kotlin")

16. Let’s try
https://github.com/ThaiKotlinDev/kotlinjs-wonderland

17. Should try
https://github.com/Kotlin/kotlin-fullstack-sample

18. Kotlin Native

19. Non-JVM Targets
- Embedded systems / IoT
- iOS
- Windows
- Web Assembly

20. Main.kt
Kotlin/Native
LLVM
Executable app

21. http://hadihariri.com/2017/05/28/raspberry-pi-starter-kit-and-kotlin-native/
import pigpio.*
fun main(args: Array<String>) {
const val port = 21
if (gpioInitialise() < 0) {
println("Error initialising")
} else {
if (gpioSetMode(port, PI_OUTPUT) < 0) {
println("Could not set mode for GPIO$port")
} else {
if (gpioWrite(port, 1) < 0) {
println("Could not write to GPIO$port")
}
}
}
}

22. http://justmaku.org/2017-06-07-kotlin-on-ios
Kotlin Native
C++ Wrapper
Objective-C Bridging Header
Swift

23. Try it
https://github.com/JetBrains/kotlin-native/tree/master/samples

24. Swift to Kotlin
https://github.com/angelolloqui/SwiftKotlin

25. Christopher Ng
Kotlinian @
Editor @ blacklenspub.com
"Thank you".repeat(infinity)