Kotlin/js IS IT A THING? Alexey Buzdin, MARCH 2017 

Me WRITING Mobile AND Java STUFF ORGANIZING events SPEAKING AT conferences TEACHING people 

Kotlin IS IT A THING? 

GREAT AT ANDROID! 

“She turned to the sunlight And shook her yellow head, And whispered to her neighbor: "Winter is dead.” - A.A. MILNE, When We Were Very Young https://spring.io/blog/2016/02/15/developing-spring-boot-applications-with-kotlin 

https://github.com/gradle/gradle-script-kotlin 

Kotlin/js 

INSTALL KOTLIN brew install kotlin 

Let’s create HelloKotlin.kt fun main(args: Array) { println("Hello JavaScript!") } 

Let’s create HelloKotlin.kt fun main(args: Array) { println("Hello JavaScript!") } Let’s compile it to javascript kotlinc-js -output out/sample-library.js -meta-info HelloKotlin.kt 

Let’s create HelloKotlin.kt fun main(args: Array) { println("Hello JavaScript!") } Let’s compile transpile it to javascript kotlinc-js -output out/sample-library.js -meta-info HelloKotlin.kt 

GENERATED CONTENT *.META.JS - METAINFORMATION FOR REFLECTION 

if (typeof kotlin === 'undefined') { throw new Error(“Error loading module …”); } this['sample-library'] = function (_, Kotlin) { 'use strict'; var println = Kotlin.kotlin.io.println_s8jyv4$; function main(args) { println('Hello JavaScript!'); } _.main_kand9s$ = main; Kotlin.defineModule('sample-library', _); main([]); return _; }(typeof this['sample-library'] === 'undefined' ? {} : this['sample-library'], kotlin); 

Console Output THE KOTLIN STANDARD LIBRARY IS ALSO ON NPM! 

HELP 

Running with GRADLE buildscript { ext.kotlin_version = '1.1.1' 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" } 

ALL LANGUAGE FEATURES IN KOTLIN 1.1 WORKS IN JavaScript! 

ALL JS LIBRARIES ARE AVAILABLE IN KOTLIN! Use ts2kt to convert type definitions http://definitelytyped.org 

THANK YOU! Q&A Follow me on Twitter @ALEXEYBUZDIN