Javascript failing. Multiple engine support?

[Osiris-Team]

The issue:
When trying to download a jar file from https://spigotmc.org we get a "default values inside destructuring assignments are not supported" exception.
The root of this problem lays at the javascript engine used by htmlunit (mozilla/rhino#756).
We have two possible fixes:

1. Integrating another javascript(graaljs) engine. Javascript failing. Multiple engine support? #201 (comment)
2. Adding support for default values inside destructuring assignments in the rhino engine Support ES2015 default values inside destructuring assignments mozilla/rhino#756

Status:

1. A lot of work, due to htmlunits strong dependency on rhino. Seems almost impossible for one single person with little insight to htmlunit (me)
2. No feedback from the authors. Also, rhino is updated very infrequently(Support ES2015 default values inside destructuring assignments mozilla/rhino#756)

The code: #201 (comment)

[rbri]

Can you please give the latest snapshot build a try.

[Osiris-Team]

Can you please give the latest snapshot build a try.

Sure gimme a min...

[Osiris-Team]

@rbri
Ok I'm running on the latest snapshot now. Btw the maven stuff didnt work, I had to add it as repository, not just in distributionManagement (see code below).

The download is still failing but now the error messages are different: https://pastebin.com/7QrYLxkj

    <repositories>
        <repository>
            <id>sonatype</id>
            <url>https://oss.sonatype.org/content/repositories/snapshots</url>
        </repository>
    </repositories>

<distributionManagement>
        <snapshotRepository>
            <id>sonatype-nexus-snapshots</id>
            <url>https://oss.sonatype.org/content/repositories/snapshots</url>
        </snapshotRepository>
</distributionManagement>

[Osiris-Team]

@rbri
Ok it seems like the download link was pointing to the jars thread/html page and not the actual jar. Sry my bad!
So I changed the test download links and added some options to show the pages content before/after waiting 7 secs.
But the issue still exists even when the download link is correct.
Here is the console output: https://pastebin.com/PGGBLbD4 (This was tested on the latest snapshot btw)

[rbri]

Looks like the js code uses one of the js features not supported by rhino at the moment.

Frome the Rhino sources

            // default values inside destructuring assignments,
            // like 'var [a = 10] = b' or 'var {a: b = 10} = c',
            // are not supported
            reportError("msg.destruct.default.vals");

[Osiris-Team]

@rbri Ok so the only option I have is to wait, till support is added?
I created an issue there: mozilla/rhino#756

[Osiris-Team]

@rbri Is there a way I can add support for default values inside destructuring assignments by myself to rhino?
What are the classes responsible for this?
I already forked the repo.

[Osiris-Team]

@rbri Or is there any other program similar to Htmlunit I could use, where default values inside destructuring assignments are supported?

[Osiris-Team]

@rbri How about adding support to change the javascript engine?
There are alternatives like:
https://www.graalvm.org/
or
https://michel-kraemer.github.io/citeproc-java/
or
https://github.com/eclipsesource/J2V8
They seem to have also a better performance than rhino.

[rbri]

This is a valid point but this is a really huge amount of work. There are many classes providing all the browser specific functionality and the whole work on HtmlUmit is since years done only by me in my spare time. Any help is welcome. Am 22. August 2020 11:39:11 MESZ schrieb Osiris Team <notifications@github.com>:

…

@rbri How about adding support to change the javascript engine? There are alternatives like: https://www.graalvm.org/ or https://michel-kraemer.github.io/citeproc-java/ or https://github.com/eclipsesource/J2V8 -- You are receiving this because you were mentioned. Reply to this email directly or view it on GitHub: #201 (comment)

-- Diese Nachricht wurde von meinem Android-Gerät mit K-9 Mail gesendet.

[Osiris-Team]

@rbri Ok I would really like to help. I will do some more research on this topic before, and see which of the engines supports default values inside destructuring assignments.
Oh and there is a great chrome extension to display github notifications: https://chrome.google.com/webstore/detail/notifier-for-github/lmjdlojahmbbcodnpecnjnmlddbkjhnn?hl=de

[Osiris-Team]

@rbri
Citeproc (https://michel-kraemer.github.io/citeproc-java/) seems to integrate 3 different javascript engines (graalvm, jre and v8).
After some testing it looks like the graalvm engine is the only one supporting default values inside destructuring assignments.
By integrating this engine it should be possible to fix my issue ;)
I'm slowly getting into htmlunits JavaScriptEngine class and I'll try to implement this.
Checkout my fork for status of implementation: https://github.com/Osiris-Team/htmlunit
Compare with master: master...Osiris-Team:master

Here is the example:

package com.osiris.JavaScriptExecutor.javascript;

import de.undercouch.citeproc.script.ScriptRunner;
import de.undercouch.citeproc.script.ScriptRunnerFactory;

import java.io.*;

public class GitHubExample {

    private static ScriptRunner scriptRunner = null;

    public static void main(String[] args) {

        // Loop 3 times to test the same operation on different engines
        for (int i = 0; i < 3; i++) {
            // Select the engine
            setEngine(i);
            System.out.println("Testing engine "+i+"...");

            // Example to run javascript from a string:
            try{
                // Test JS code to check if default values inside destructuring assignments are supported
                String destruct_test = "const dummy = {" +
                        "  name: undefined" +
                        "};" +
                        "const { name = 'Peter' } = dummy;" +
                        "console.log(name)";

                // Get the input stream of the selected string
                InputStream in = new ByteArrayInputStream(destruct_test.getBytes());
                Reader reader = new InputStreamReader(in);

                // Run the javascript
                scriptRunner.eval(reader);
                System.out.println("Engine "+i+" completed successfully!");
                // Result is that only the graal-engine will finish successfully
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * Select the engine:
     * 0 = graal_engine (default);
     * 1 = java_engine;
     * 2 = v8_engine;
     * @param engine
     */
    public static void setEngine(int engine){
        if (engine==0){
            //Select graal_engine
            ScriptRunnerFactory.setRunnerType(ScriptRunnerFactory.RunnerType.GRAALJS);
            scriptRunner = ScriptRunnerFactory.createRunner();
        }
        else if (engine==1){
            //Select java_engine
            ScriptRunnerFactory.setRunnerType(ScriptRunnerFactory.RunnerType.JRE);
            scriptRunner = ScriptRunnerFactory.createRunner();
        }
        else {
            //Select v8_engine
            ScriptRunnerFactory.setRunnerType(ScriptRunnerFactory.RunnerType.V8);
            scriptRunner = ScriptRunnerFactory.createRunner();
        }
    }

}

[Osiris-Team]

@rbri
I need to modify the htmlunit-core-js jar to implement a new engine. Is the source code available somewhere?

[rbri]

https://github.com/HtmlUnit/htmlunit-core-js

[Osiris-Team]

@rbri Im back with some news. I think implementing the GraalJS Engine into htmlunit is quite much impossible (at least for me alone) because of its strong dependency and interconnectivity with the rhino engine, like you said. That's why I created this https://github.com/Osiris-Team/JG-Browser which is the same as htmlunit just built with the graal js engine as base. What do you think?

[rbi]

@Osiris-Team you probably mean @rbri, not @rbi

[Osiris-Team]

Ups!

[kerbymart]

@Osiris-Team so it seems the RhinoJS is the one that needs to be updated to make HtmlUnit more robust to handle javascript...