How to call beautify.js from Java using GraalJS

JavascriptBeautifierForJava.java

// https://github.com/beautify-web/js-beautify
// https://github.com/oracle/graaljs
// Inspired by https://gist.github.com/fedochet/d41442e735eaa277937a094ab8e5fc8f

import org.apache.commons.io.IOUtils;
import org.graalvm.polyglot.Context;
import org.graalvm.polyglot.HostAccess;
import org.graalvm.polyglot.PolyglotAccess;
import org.graalvm.polyglot.Value;

import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;

public class JavascriptBeautifierForJava {

    private static final String BEAUTIFY_JS_RESOURCE = "lib/beautify.js";
    private static final String BEAUTIFY_METHOD_NAME = "js_beautify";

    private static JavascriptBeautifierForJava instance;

    public static JavascriptBeautifierForJava getInstance() {
        if (instance == null) {
            instance = new JavascriptBeautifierForJava();
        }
        return instance;
    }

    private Context context = null;
    private Value v = null;

    private JavascriptBeautifierForJava() {
        context = Context.newBuilder("js")
                .allowHostAccess(HostAccess.NONE)
                .allowHostClassLookup(cl -> false)
                .allowIO(false)
                .allowPolyglotAccess(PolyglotAccess.NONE)
                .build();

        context.eval("js", "var global = this;");
        InputStream is = getClass().getClassLoader().getResourceAsStream(BEAUTIFY_JS_RESOURCE);
        try {
            String module = IOUtils.toString(is, StandardCharsets.UTF_8);
            context.eval("js", module);
            v = context.eval("js", "(function(a, b) { return " + BEAUTIFY_METHOD_NAME + "(a, b) })");

        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public String beautify(String javascriptCode) {
        return v.execute(javascriptCode, null).asString();
    }

    public static void main(String[] args) {
        String unformattedJs = "var a = 1; b = 2; var user = { name : \n \"Andrew\"}";

        JavascriptBeautifierForJava javascriptBeautifierForJava = getInstance();
        String formattedJs = javascriptBeautifierForJava.beautify(unformattedJs);

        System.out.println(formattedJs);
    }
}