Await Promise

Awaiting a JavaScript Promise in Rust sounds crazy, but it’s feasible in NAPI-RS.

💡

Awaiting a JavaScript Promise needs the tokio_rt and napi4 features to be enabled.

lib.rs

use napi::bindgen_prelude::*;
 
#[napi]
pub async fn async_plus_100(p: Promise<u32>) -> Result<u32> {
  let v = p.await?;
  Ok(v + 100)
}

test.mjs

import { asyncPlus100 } from './index.js'
 
const fx = 20
const result = await asyncPlus100(
  new Promise((resolve) => {
    setTimeout(() => resolve(fx), 50)
  }),
)
 
console.log(result) // 120

External Types Overwrite