Function napi::bindgen_prelude::get_js_function

pub fn get_js_function(
    env: &Env,
    raw_fn: ExportRegisterCallback
) -> Result<JsFunction>

Get JsFunction from defined Rust fn

#[napi]
fn some_fn() -> u32 {
    1
}

#[napi]
fn return_some_fn() -> Result<JsFunction> {
    get_js_function(some_fn_js_function)
}

returnSomeFn()(); // 1