Loading the default export from a JS module?

[mythmon]

I'd like to write Rust code with deno_core that is functionally equivalent to

import foo from "./module.js";

I have bumbled around a bit, and this is what I have, but I feel like I'm missing something key. The output I get boils down to obj = (), which I take to mean "undefined". I've also tried replacing the string "default" with the names of top level consts in the script; it produces the same () output.

use anyhow::Result;
use deno_core::{JsRuntime, ModuleSpecifier};
use std::{path::Path, rc::Rc};

pub fn load_scene(path: &Path) -> Result<()> {
    let path = path
        .to_str()
        .ok_or_else(|| anyhow::anyhow!("Could not convert path to str"))?;
    let main_module = deno_core::resolve_path(path)?;

    let mut js_runtime = deno_core::JsRuntime::new(deno_core::RuntimeOptions {
        module_loader: Some(Rc::new(deno_core::FsModuleLoader)),
        ..Default::default()
    });

    let tokio_runtime = tokio::runtime::Builder::new_current_thread()
        .enable_all()
        .build()?;
    tokio_runtime.block_on(run_script(&mut js_runtime, &main_module))?;

    Ok(())
}

async fn run_script(js_runtime: &mut JsRuntime, specifier: &ModuleSpecifier) -> Result<()> {
    let mod_id = js_runtime.load_main_module(specifier, None).await?;
    let result = js_runtime.mod_evaluate(mod_id);

    js_runtime.run_event_loop(false).await?;
    result.await??;

    let global = js_runtime.get_module_namespace(mod_id)?;
    let namespace = global.open(js_runtime.v8_isolate());
    let mut scope = js_runtime.handle_scope();
    let default_key = serde_v8::to_v8(&mut scope, "default")?;
    let default_value = namespace.get(&mut scope, default_key).ok_or_else(|| anyhow::anyhow!("no default"))?;
    let obj = serde_v8::from_v8(&mut scope, default_value)?;
    
    dbg!(default_key, default_value, obj);
    Ok(())
}


#[cfg(test)]
mod tests {
    use std::{path::PathBuf, str::FromStr};
    use crate::load_scene;

    #[test]
    fn test() {
        let path = PathBuf::from_str("./test_data/basic.js").unwrap();
        load_scene(path.as_path()).unwrap();
        assert!(false);
    }
}

[bartlomieju]

What is the content of the file you're trying to import?

[Abdillah]

I guess something like

export default "Test value";

How exactly we get the "Test value" into the Rust world?

[rouzwelt]

did you figure out how to extract the default export of a module?
Im running into the same issue now, would appreciate any tips/help.
@bartlomieju @mythmon