Compile kotlin code to both JVM and JavaScript

Question

I really like the idea of coding a framework once, and then being able to compile it as jvm byte code as well as to javascript for web use.

Is this currently possible with the kotlin compiler?

Answer 1

It is possible but you may face some difficulties. First of all you can build and configure it only with Maven: just setup both executions. The second issue is that IDE can't deal with multiple targets so you can use tricks to enable/disable stdlib/kotlin-js-library

You can see it at https://github.com/Kotlin/kotlinx.html

It is multimodule project.. Module jvm is only compiled for JVM, module js only to javascript, module shared to both

Notice maven profiles: when you edit shared module you can enable js or jvm but not both: otherwise IDE will go crazy. During compilation both profiles are active by default so you will get multitarget jar

Answer 2

I created a projet kotlin maven targeted JVM, it can be compiled to both JVM and JS.

1. Open Intellij IDEA -> File -> new -> Project -> Maven -> check "create from archetype" -> choose "org.jetbrains.kotlin:kotlin-archetype-jvm"

2. Edit GroupId:com.example.training; ArtifactId:kotlin2js; Version:1.0-SNAPSHOT

NOTE: a name of project (module) should not contains "-" (a dash) but "_" (an underscore) is ok.

3. Create a class kotlin named Person in path src/main/kotlin/com.example.training/

   data class Person (
       val id, Int,
       val firstname: String)
   

4. Edit pom.xml

   a) Add dependency "kotlin-stdlib.js"

    <dependency>
           <groupId>org.jetbrains.kotlin</groupId>
           <artifactId>kotlin-stdlib-js</artifactId>
           <version>${kotlin.version}</version>
    </dependency>
   

   b) Add goal "js" in plugin "kotlin-maven-plugin"

   c) (Optional for interoperability Kotlin/JS) Add plugin for unpacking js files needed which are in lib "kotlin-stdlib-js"

         <plugin>
               <groupId>org.apache.maven.plugins</groupId>
               <artifactId>maven-dependency-plugin</artifactId>
               <executions>
                   <execution>
                       <id>unpack</id>
                       <phase>compile</phase>
                       <goals>
                           <goal>unpack</goal>
                       </goals>
                       <configuration>
                       <artifactItems>
                           <artifactItem>
                               <groupId>org.jetbrains.kotlin</groupId>
                               <artifactId>kotlin-stdlib-js</artifactId>
                               <version>${kotlin.version}</version>
                                                 <outputDirectory>${project.build.directory}/js/lib</outputDirectory>
                           <includes>*.js</includes>
                           </artifactItem>
                       </artifactItems>
                       </configuration>
                   </execution>
               </executions>
       </plugin>
   

   5. Run mvn clean compile

   6. Folder classes contains Person.class for java. Folder js contains kotlin2js.js and kotlin2js.meta.js for JS, all js files unpacked are in child folder lib.