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Top-Level Await for Stage 4 The Await is Over (or is it?)

Yulia Startsev - TC39 May, 2021

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Quick Refresh

  • Top-level await enables modules to act as big async functions: With top-level await, ECMAScript Modules (ESM) can await resources, causing other modules who import them to wait before they start evaluating their body.

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What has changed since March?

  • Editorial change introducing prose with an example of what happens when there is an error in an async module graph. You can read all about it here.
  • Spec readability PR. This introduces a new state - evaluating-async, between evaluating and evaluated. The change is editorial but reduces potential misreadings.
  • Open issues

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Current status

  • ✅ Test262 acceptance tests have been written for mainline usage scenarios, and merged.
  • Two compatible implementations which pass the acceptance tests
  • ✅ Integrated spec text
  • ⏹ The ECMAScript editor has signed off on the pull request

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Stage 4?

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Massive thank you to Guy Bedford, Ms2ger, Dan Ehrenberg, Tobias Koppers, Jason Orendorff, and everyone else who helped get this across the finish line!