await is a keyword used in async functions. Currently await is only used inside the async function. If you use outside async, throws an error.

With the ES13 release, You can use await without async context.

Await can be used in multiple ways.

ES13 Top-level await

top-level await used in different use cases.

  • Load modules at runtime

await is used with top-level ESM modules using imports only.

Modules won’t complete loading until await promise is settled. Resolved means successful loading module, and rejected means failed to load a module.

const modules = await import(`./modules`);
  • use await in a plain script tag:

You can use await in plain script tags.

await Promise.resolve('Resolved');

console.log('load completed');

It throws “SyntaxError: await is only valid in async functions and the top level bodies of modules

To make await work in a plain script tag, add type=“module”.

<script type="module">
await Promise.resolve('Resolved');

console.log('load completed');
  • use await in fallback for module failure We can use await for fallback use cases where the module failed to load with try-and-catch blocks.
let module;
try {
  module = await import("./module.esm");
} catch {
  module = await import("./module.esm");
  • initialization during loading

await can be used to call database-related code to initiate a connection.

const connection = await loadMongoDB();

Important notes:

  • It works top-level modules using ES6 modules(esm)
  • No Support for plain <script> tags, But you have to use <script type="module"> to make it work.