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Severity: error
Category: async-await
Stage: Stage 1

Description

Top-level await (ECMAScript 2022, ECMA-262 §15.2) is only valid in ES modules — files loaded with type="module" in browsers, or treated as ESM by a Node.js-compatible runtime.

SJS detects whether the current file is an ES module by the presence of at least one import or export declaration at the top level. A file without any such declaration is treated as a CommonJS-style script, and top-level await inside it is a type error.

Example

// ✗ error — no import/export, so not an ES module
const data = await fetch("/api/data")   // SJS-E018
console.log(data)

Fix

Option 1 — Make the file an ES module by adding at least one export:

// ✓ correct — ES module (has export)
export {}

const data = await fetch("/api/data")
console.log(data)

Option 2 — Wrap the top-level logic in an async IIFE if you intentionally cannot use ESM:

// ✓ correct — async IIFE, no top-level await
;(async () => {
  const data = await fetch("/api/data")
  console.log(data)
})()

Related codes

  • SJS-E017 — circular import detected in module graph
Documentation