Feature Request: Top level await

🙋 feature request

Parcel 2 could support Top Level Await. Most bundlers/runtimes are starting to support it so it could be nice to have it in Parcel

Webpack’s experiments.topLevelAwait experimental feature Node stable support ~Node’s(13.3+) --harmony-top-level-await/--harmony_top_level_await experimental feature~ Deno’s native support, https://github.com/denoland/deno/pull/3212 Chromium’s native support, https://bugs.chromium.org/p/v8/issues/detail?id=9344. Will ship in Chrome 89

[Banou26]

Node now officially supports top level await https://github.com/nodejs/node/commit/54746bb763ebea0dc7e99d88ff4b379bcd680964 🎉

[mischnic]

Related: https://twitter.com/bradleymeck/status/1506727720968986633 https://esm-exports-without-eval.glitch.me/

Details

the source code for c.mjs exports names: default, hi

// a.mjs
import './d.mjs';
import * as c from './c.mjs';
export function getNS() {
  return Object.getOwnPropertyNames(c);
}

// b.mjs
import {getNS} from './a.mjs';
console.log(getNS()); 
// Safari gets this right with TLA
// but V8 and SpiderMonkey incorrectly
// evaluate parents if using TLA and throwing errors
// FIXME: once V8 and SpiderMonkey allow TLA to block
//   graphs correctly move to `await new Promise` to
//   not fire off error alarms in devtools
throw getNS();
// await new Promise(()=>{})

// c.mjs
console.error('EVALUATING C, OH NO');
debugger;
export default 0;
export var hi;

// d.mjs
import './b.mjs';