reactjs-server

Renders React.js markup (or any other string) on JVM with Graal or Nashorn.

Features

• Graal.js on GraalVM with fallback to Nashorn on HotSpot
• Multiple render instances
• Watches source files and reloads automatically

Setup

resolvers += Resolver.bintrayRepo("dgolubets", "releases")
libraryDependencies += "ru.dgolubets" %% "reactjs-server" % "0.2.1"

Minimal example

import akka.actor.ActorSystem
import io.circe.Json

import ru.dgolubets.reactjs.server._

implicit val system = ActorSystem()

import system.dispatcher

val renderSource = ScriptSource.fromString(
  """
    |function render(state){
    |  return "<h1>state.title</h1>"
    |}
  """.stripMargin)

val renderServer = new RenderServer(RenderServerSettings(Seq(renderSource)))

renderServer.render("render", Json.obj("title" -> Json.fromString("Some title"))).map { html =>
  println(html)
}

Using Graal.js

You don't have to do anything but to start your application with GraalVM. ReactJS server will try to instantiate Graal.js context by default and if it's not available - will fallback to using Nashorn.

Providing polyfills

ReactJS server comes with a minimal set of polyfills for logging via console. The server will execute specified sources in the order provided, so it's easy to include your own polyfills by just adding them before your main script.

Watching file sources

To watch for source file changes, specify watch settings with root pointing to some parent directory of your source files.

val renderSource = ScriptSource.fromFile(new File("path/to/my/source.js");

val watchSettings = WatchSettings(
  root = new File("path/to"), // watch root
  delay = 1 second // delay to aggregate file changes
)

val renderServer = new RenderServer(RenderServerSettings(
  Seq(renderSource), 
  watch = Some(watchSettings)
)

Starting multiple instances

By default the server is gonna start an instance per CPU core, but you can override it.

val renderServer = new RenderServer(RenderServerSettings(
  Seq(renderSource), 
  nInstances = 2
)

Performance

Both Graal.js and Nashorn can reach Node.js performance after a warmup (100-1000+ iterations per instance). Warm up times are likely to be improved in future Graal versions.

Using with Webpack

Create a separate configuration to bundle a library:

output: {
  filename: "scripts/server.js",
  library: "mylib",
  libraryTarget: "var"
}

Export a render function in your index source file:

export function renderToString(state: any): string {
    return ReactDOM.renderToString(<Root />);
}