Pass an array from C# to JavaScript

We have a JavaScript Office add-in. We are making an installable and executable add-in on top of it by VSTO and WebView2.

I just realize that it's not obvious to pass an array value from C# to JavaScript. For instance, on the side of C#, I have the following code:

public object test()
{
    int[,] xx = { { 1, 2, 3 }, { 3, 4, 5 } };
    return xx;
}

In JavaScript, I have

test () {
    return new Promise(async (resolve, reject) => {
        try {
            let result = await window.chrome.webview.hostObjects.control.test();
            console.log(result)
            console.log(JSON.stringify(result))
            resolve(result)
        } catch (error) {
            reject(error)
        }
    })
}

Then, in the console of JavaScript, it shows Array(0) and []. If I pass a string value from C# to JavaScript, it works well.

Does anyone know how to pass an array from C# to JavaScript?

You must serialize objects and arrays to any format that suits your needs. But I think for JavaScript the most suitable format would be a JSON string, so you could get a ready made object in JavaScript. See Serialize c# array of strings to JSON array for more information.