WASM - Passing JS objects to D

[JN via Digitalmars-d-learn]

What is the recommended way to pass JS objects to D when doing 
WASM?

My current solution is to maintain an ID <-> object mapping in 
JS, something like:

const mapJsToHandle = new WeakMap();
const mapHandleToJs = {};
var id = 0;

const toHandle = (x) => {
    if (!mapJsToHandle.has(x))
    {
        id++;
        mapJsToHandle.set(x, id);
        mapHandleToJs[id] = new WeakRef(x);
        return id;
    } else {
        return mapJsToHandle.get(x);
    }
};

const fromHandle = (x) => {
    return mapHandleToJs[x].deref();
};

which I can use like:

const drawJS = (imghandle, x, y) => {
    document.ctx.drawImage(fromHandle(imghandle), x, y);
}

var img = new Image();
drawImage(toHandle(img))

============
D code
============
extern(C) void drawImage(int imghandle)
{
    draw(imghandle, 100, 100);
}

void drawJS(int imghandle, double x, double y);



This works. But I wonder if there's some easier/better way? If I 
understand correctly you can only pass primitive objects and 
arrays across the boundaries.