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1. Clone sample repository and move to the newly cloned directory.
2. Make sure that JAVA_HOME points at a JDK11 (or later) export JAVA_HOME=/path/to/jdk11.
3. Open VSCode with VSNetBeans installed.
4. Go to File | Preferences and In VS Code, go to Preferences | Settings, search for netbeans.jdkhome jdkhome, and set it to to /path/to/jdk11 (or later).
5. Open Folder with graal-js-jdk11-maven-demo in VSCode.
6. Remove App.java and AppTest.java originally coming with the sample Maven project.

Development

1. Into In main/java/com/mycompany/app, add a new file named PolyglotSample.java with the following code:

   Code Block
   language java title PolyglotSample.java linenumbers true collapse true
   package com.mycompany.app; import org.graalvm.polyglot.Context; import org.graalvm.polyglot.Source; import org.graalvm.polyglot.Value; import java.net.URL; public class PolyglotSample { public static void main(String[] args) throws java.io.IOException, java.lang.InterruptedException { Context ctx = Context.create(); URL fibUrl = PolyglotSample.class.getResource("fib.js"); Source fibSrc = Source.newBuilder("js", fibUrl).build(); Value fib = ctx.eval(fibSrc); for (int i = 0; i < 10; i++) { Value res = fib.execute(i); System.out.println("Polyglot with Graal.JS - fib(" + i + ") = " + res.asInt()); Thread.sleep(500); } } }

   
   

2. In terminal or file explorer, create Create the following structure to store the JS source file, so that Java can find it, within the main folder: resources/com/mycompany/app

3. Inside In this resources/com/mycompany/app folder, create a file named fib.js and paste in the following JS code:

   Code Block
   language js title fib.js linenumbers true collapse true
   (function(n) { function fib(x) { if (x <= 2) { return 1; } let fibX1 = fib(x - 1); let fibX2 = fib(x - 2); return fibX1 + fibX2; } let fibN = fib(n); print(`JavaScript computed that fib(${n}) is ${fibN}`); return fibN; })

   
   

4. Save all files and invoke action from Command Palette: Java: Compile Workspace
   • this is the action provided by VSNetBeans which builds the project.
   • Project is normally built also when debugger start but it is worth for the 1st time see if maven build passes.

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