TeaVM Works with Google Apps Script - Documentation Request

[ivan-velikanov]

TeaVM Works with Google Apps Script - Documentation Request

Summary

I've successfully tested TeaVM 0.10.2 with Java 21 in Google Apps Script environment and found it works well. Since this integration doesn't appear to be documented. It should be documented because otherwise general google search doesn't reveal anything, and if you ask Claude or any AI ... they simply tell it won't work.

So I wanted to share the working configuration here in the dicussions for the search engines to pick up if anybody tries to look for this, and wanted to request if some mention of this could be added in the official documentation (just a single line something which says that teavm works inside google appscript environment, and perhaps point to this dicussion thread).

Environment Tested (standard - nothing special)

• TeaVM Version: 0.10.2
• Java Version: 21
• Target Environment: Google Apps Script

What Works

1. Set up 2 projects - (a) standard maven/gradle TeaVM project (b) a clasp js project for Google Appscript (GAS)
2. JSExport Functions: Individual Java methods can be exported and called directly from JavaScript (examples below)
3. JSO Interfaces: Google Apps Script APIs can be accessed from Java using JSO (examples below)
4. Basic Compilation: Java 21 code compiles successfully to JavaScript (standard config, nothing special)
5. Copy the generated js to the claps project (you might need to add some config in your build to do that automatically)
6. Entry GAS js file (Code.js / Code.gs) would need to have the following at the top of the file, otherwise appscript functions will not be able to access TeaVM exported functions :

var global = this;
var exports = {};
var module = { exports: exports };

7. The Code.js can just provide simple shim functions facing the spreadsheet calls, and simply delegating to the TeaVM exported functions
8. Push all files to your appscript using clasp once done.
9. Test.

Java Code Example (standard Teavm approach - nothing special)

@JSExport
public static int generateRandomNumber() {
    return (int) (Math.random() * 1000) + 1;
}

@JSExport
public static void setSpreadsheetValue(String cellAddress, int value) {
    SpreadsheetApp.getActiveSpreadsheet()
        .getActiveSheet()
        .getRange(cellAddress)
        .setValue(value);
}

JSO Interface Example (standard Teavm approach - nothing special)

These are just some samples, for making things work you will have to create all required class definitions for mapping to the GAS apis.

public final class SpreadsheetApp {
    private SpreadsheetApp() {}

    @JSBody(script = "return SpreadsheetApp.getActiveSpreadsheet();")
    public static native Spreadsheet getActiveSpreadsheet();

    @JSBody(params = "id", script = "return SpreadsheetApp.openById(id);")
    public static native Spreadsheet openById(String id);
}

public interface Range extends JSObject {
    @JSBody(params = "value", script = "return this.setValue(value);")
    Range setValue(int value);

    @JSBody(script = "return this.getValue();")
    Object getValue();
}

IMPORTANT : Google Apps Script Integration

This is simple, but this is the only extra configuration you need to do to make it work. The following needs be added in Code.js (Code.gs) as GAS is slightly different from browser environment. Without this exported teavm modules/functions will not be accessible to GAS functions.

// Setup required for TeaVM module loading
var global = this;
var exports = {};
var module = { exports: exports };

// After including generated JavaScript, functions are available
function test() {
    var num = generateRandomNumber(); // Works directly
    setSpreadsheetValue('A1', num);   // Works directly
}

If anyone needs more details about the implementation or have questions about the integration, I'm happy to provide additional information.

Thank You

Thanks to @konsoletyper I have full java/jvm stack for "everything", I don't need to go anywhere else. TeaVM successfully bridges Java and JavaScript environments, including Google Apps Script. Few years ago I used to use jsweet but it was kind of cumbersome, teavm is very clear and powerful. The fact that it has the ability to use Java 21 features is more than I can ask for (even jdk25 doesn't have any extraordinary new language feature that i need to be bothered about).

(Edit: the jso examples were ai-extracts of the code i tested, and it was slightly wrong, corrected it)

[konsoletyper]

TeaVM Version: 0.10.2

Why not the latest one?

wanted to request if some mention of this could be added in the official documentation

Definitely not. There are plenty of possible use cases for TeaVM, I just can't cover/verify/document/maintain all of them. So I'd like to be somewhat decentralized. TeaVM is a compiler, and you can build whatever communities/projects that utilize it. However, I realize that it could be useful to have some centralized place where users could share their ideas, but being engineer person, not marketing person, I have neither idea how to do it, nor any willingness and time for it.

the jso examples were ai-extracts of the code i tested, and it was slightly wrong, corrected it

Not sure it will work with 0.10:

@JSClass
public final class SpreadsheetApp extends JSObject {
    private SpreadsheetApp() {}

    public static native Spreadsheet getActiveSpreadsheet();

    public static native Spreadsheet openById(String id);
}

public interface Range extends JSObject {
    Range setValue(int value);

    Object getValue();
}

[konsoletyper]

Except for the last case, all @JSBody can be removed, since they don't add any value. Also, since recent versions of TeaVM (I believe, it's 0.10.0) you can also avoid trivial @JSBody for representing static methods.

[ivan-velikanov]

I am sorry, I am not fully clear. I understood jsbody can be removed in most of the places. So after version 0.10.0 it is still required in the last class definition SpreadsheetApp .... is my understanding correct?

[konsoletyper]

I'm not sure about particular version, but in latest TeaVM you can use alternative way of representing SpreadsheetApp, as I described above. As for other classes, you can avoid @JSBody even in ancient versions of TeaVM, perhaps even in 0.1.0

[konsoletyper]

Never trust AI

[ivan-velikanov]

Ok now I understood, thank you. Sorry for the trouble the AI generated code caused, thanks for the patient guidance.