The JavaScript exception "await is only valid in async functions, async generators and modules" occurs when an await expression is used outside of async functions or modules or other async contexts.

Message

SyntaxError: await is only valid in async functions and the top level bodies of modules (V8-based)
SyntaxError: await is only valid in async functions, async generators and modules (Firefox)
SyntaxError: Unexpected identifier (Safari)

Error type

SyntaxError.

What went wrong?

JavaScript execution is never blocking: an await can never block the execution of the program. Instead, it pauses the execution of the surrounding async task, while allowing other tasks to continue running. Therefore, await cannot be used in sync tasks, such as functions, generator functions, or top level of scripts. It is not always apparent whether the current file is a script or a module — see the Modules guide for more information.

Examples

Top-level await

You cannot use await at the top level of a script:

<script>
  await fetch("https://example.com");
  // SyntaxError: await is only valid in async functions, async generators and modules
</script>

Instead, make the script a module:

<script type="module">
  await fetch("https://example.com");
</script>

Async callbacks

You cannot use await in a sync callback:

urls.forEach((url) => {
  await fetch(url);
  // SyntaxError: await is only valid in async functions, async generators and modules
});

Instead, make the callback async. See more explanation in the Using promises guide.

Promise.all(
  urls.map(async (url) => {
    await fetch(url);
  }),
);

See also

• await