How did you know Javet?

[caoccao]

First of all, thank you for choosing Javet.

I'm asking you to do me a favor by spending little time answering few questions.

1. How did you know Javet?
2. What are you using Javet for?
3. Do you have any suggestions?

Thank you 😊

[Vshnv]

1. It was recommended by a friend on the project as a replacement for J2V8 as its maintainers decided to maintain bindings for Android only.

2. A placeholder system which allows users to evaluate javascript in text used in a game.

3. It would be great if we could provide a URL or sorts of where the library should look for its binaries to be copied to the temp directory, as currently it sometimes requires to be loaded into a isolated environment with that path with the binaries as the root URL in the classpath to actually find the binaries.
   For eg: Project A loads a Project B, binaries are in Jar of B, but Javet looks for the binaries in the jar of A since it uses ClassLoader#getResource directly.

[caoccao]

3. It would be great if we could provide a URL or sorts of where the library should look for its binaries to be copied to the temp directory, as currently it sometimes requires to be loaded into a isolated environment with that path with the binaries as the root URL in the classpath to actually find the binaries.
   For eg: Project A loads a Project B, binaries are in Jar of B, but Javet looks for the binaries in the jar of A since it uses ClassLoader#getResource directly.

Thank you for the feedback. I have similar concern on the current way of loading the library. I think I'll keep the current way until there are enough requirements outlining a better way. You are welcome creating an issue with your detailed requirements.

[Cormanz]

I think I found this when I was searching for an engine better then GraalJS to run JS code in Java, and came across Javet. That's as much as I remember.

[caoccao]

I think I found this when I was searching for an engine better then GraalJS to run JS code in Java, and came across Javet. That's as much as I remember.

Thank you for sharing that. I have to admit Javet gets really low page rank and it's hard to reach the surface. I wonder how Javet users could promote Javet in public space.

[orvitpng]

1 | @Cormanz recommended it to me in a project we were working on.
2 | A Minecraft plugin which will allow you to write code using JS/TS for software usually programmed in Java.
3 | I don't know if this is already available, but a Gradle development repo.

[caoccao]

Thank you for the feedback.

Regarding (3), I don't quite get it. What do you mean by a Gradle development repo?

[orvitpng]

Sorry for my miswording, I'm having troubles building the dev version for 0.9.7 and just looking for an easy way to get it lmao. Not that great with everything.

My build script wont work, and I'm just overall confused lmao.

[caoccao]

Yes, having a successful build is very challenging even with the detailed guide.

Regarding the issue you posted, I recommend not to reference a Windows path in WSL.

[orvitpng]

Alright. I'll retry on my wsl file. Also do you need both .so and .dll files, or can it be either one of them.

[caoccao]

If you stick to one OS, you only need one lib format.

• Linux - .so
• Windows - .dll

[cout970]

1. I tried several JS engines for Java, but most of them didn't had support for modern features, I searched on google for Java V8 bindings and I found J2V8 which doesn't work on outside of android. Then finally found Javet which works perfectly and is up to date.
2. I'm building a game engine in Kotlin with JS scripting support, It's a hobby project so I will probably abandon it in a few weeks.
3. I think having more documentation comments on functions would be great, especially on V8Runtime.java,
   also I don't know how feasible it is, but in IV8Convertible.toObject() knowing the value of T would be very useful, maybe passing the class of T as an optional argument?, in my usecase I need to convert a JS function into a Java lambda for an Event system, and there is no way of knowing the number of arguments required by Java

[caoccao]

Thank you for the sharing. Best wishes to your personal project.

Regarding (3):

• Javet outsources the object conversion to the converters. So if you check the converters out, you will find such API.
• It's similar to the modern JSON libraries: Is the conversion recursive or non-recursive? Passing a type in doesn't answer this question well. More options have to be provided to represent recursive vs. non-recursive, how to handle circular structure, recursion depth, etc. Again, Javet leaves those to the converters.
• Ownership of V8 reference objects cannot be easily managed with this kind of API, because it implies a split of ownership between the source instance and target instance both of which can function well and be recycled?. In order to support that well, I suspect Javet has to implement something like shared_ptr in Java. That's too heavy and still cannot completely resolve the issues.

[stephan-ansems]

Hi @caoccao,

Sure i'll help:

1. I found Javet after a long search on how to implement scripting in a Java application. After some convoluted DSL implementations i figured out that Nashorn is an option (i'm not a seasoned developer) but quickly found out that it's javascript syntax is outrageously outdated. So back to google... searching for v8 support and finally found it.
2. As said i want to use it to allow users of the application to enhance the application with some custom scripts. The application is just a proof of concept.
3. a. I would like more documentation that is dumbed down a lot. I'm no hard-core java or javascript developer and this interop stuff is quite complicated. So having a simpler or at lease more gentle documentation would help. No offence, your documentation is correct, but it takes a lot of effort to get to the same knowledge level as you and the documentation seems to assume i already have this knowledge.
   b. The API seems complex so what i'm doing is a lot of wrapper classes to make working with Javet simpler. I know that i might break some things that i'm not aware of and doing this limits the possible usecases, but i feel the need to do it ;-)
   c. Have a more out-of-the-box integration with the sl4j logging framework. For this i also wrote two simple wrapper classes, one for the console and one for the engine. It seems a strange to me that these two are different as well...
   d. Maybe get Baeldung of the likes to make some tutorials on Javet

[caoccao]

Thank you for the sharing. They all make sense.

Regarding (1), I wish more and more Javet users help promote it in public. So far, I'm playing the dominant role in that. Ironically, some tech sites treat me poorly because they think I'm self-promoting.

Regarding (2), yes, Javet is a perfect SDK for that purpose. Many Minecraft developers build mods with Javet.

Regarding (3),

a) I think that's a trade-off between time and depth of knowledge. I have to assume Javet users have deep understanding on Java and JavaScript so that I may save some effort on the documentation. Especially, this is a personal project without proper funding. My current strategy is: You raise your voice, you get what you need.

b) Sure, Javet is designed to encourage Javet users to go that way.

c) Javet has zero dependencies to other Java libraries. That makes some easy things difficult. But, that gives Javet users full control over the libraries they want to introduce. I believe it's subtle effort to write a few wrappers with tens of lines of code. Dependency hell is a much more horrible thing, I suppose.

d) Good idea. I'm not sure how that will work. Any more suggestions?

[54754N4]

First of all thank you for creating Javet, i'm quite happy with it until now.

1. How did you know Javet?
   I basically used to use Nashorn, then moved to GraalJS before they've both been deprecated. After a labourous search I finally found Javet and saw that it supported modern JS through node which was quite enticing.
2. What are you using Javet for?
   Many of my projects ended up using it. One of them being my discord bot which allows me to run quick JS code, another is a JSFuck interpreter where I needed to be able to execute any random JS since a lot of the code uses the "Function" constructor, however I didn't want to implement a full-blown JS interpreter so Javet came to be quite handy. I especially loved the fact that JS data types have their own V8Value classes, it allowed me to easily swap between V8Value classes and my AST nodes quite easily.
3. Do you have any suggestions?
   Probably adding more detailed comments could prove to be helpful since the community is quite small and not many people have used Javet on stack overflow and other websites. So if we have a question or a small issue it's quite hard to find the information in the javadoc (especially since there's no search bar in the javadoc somehow ? xD Unless i'm using the wrong docs but this is the docs i'm referring to)

[caoccao]

Thank you for the excellent sharing.

I'm very happy to know that Javet helps de-obfuscate JS code and like the approach you took. Regarding the javadoc, yes, a lot of API do not have rich documentation. I think that would last for quite a long time as I don't have the luxury of time for that.

[54754N4]

This is perfectly understandable, most of the important things are well documented on the website so it poses no issues for most of us. Thanks already for the amazing project!
Edit: Thanks for the comment you've made on one of my commits, thanks to that I managed to use the latest Javet version now that I know how to disable strict mode haha

[caoccao]

No problem. Javet evolves based on the user feedback. The beauty of open source projects.

[bananasmoothii]

1, 2. I am making a Blockly interface that exports JavaScript code. I then tried Nashorn until finding out that it wasn't supported anymore. Then I switched to GraalVM JS until finding out that it was terribly slow when not using GraalVM. I then searched for alternatives again and found Javet in an updated StackOverflow answer (before, it was pointing to J2V8)

3. When there is an exception, also show the js code and the js stacktrace if it has any implication in the error

[caoccao]

Thank you for sharing your story.

Yes, GraalJS is slow and J2V8 is outdated. Welcome to the Javet world!

[gleno]

How did you know Javet?
Found it as an alternative to J2V8, which is no longer maintained. Also had a play with GraalJS, which I found hard and unintuitive to use. The whole Graal ecosystem feels very unfriendly to me.

What are you using Javet for?
At the moment, I am not using it, but I've kept following this project, and for my previous projects I often needed functionality like evalJs("1+1"), and evalJs("host.callApi()"). Typically I rolled my own primitives like setTimeout(), and prefer own primitives for promises. The goal is typically to allow integration with something I'm building from 3rd parties. Javascript is awesome for this, because how easy it is to use, but for some reason - there's no good Java JS interop. All good projects so far have sunset.

Do you have any suggestions?
You're doing an awesome job. For my use cases, I don't need node-like functionality. If it's easy or hard for you to maintain, I don't know - but if it gets too much of a hassle, maybe consider dropping node.

[caoccao]

Thank you for the excellent sharing. The answers all make perfect sense.

• Project Javenode might worth your time as it implements some typical API like setTimeout, console.log and the event loop.
• The Node.js support is critical to 50+% of Javet usages. It might not be as hard as you think. So I'll keep it supported.

[wrenashe]

Considering J2V8 and then Javet shows up somewhere else and looks more charming. https://www.caoccao.com/Javet/faq/background/history_with_j2v8.html.

And thanks for sharing a nice thing!