is-awaitable

A lightweight solution for detecting async functions (including async generators).

Installation

Using npm:

$ npm install is-awaitable

Using yarn:

$ yarn add is-awaitable

Using pnpm:

$ pnpm add is-awaitable

CDN Usage

You can use is-awaitable directly in browsers via CDN:

<script src="https://unpkg.com/is-awaitable@latest/dist/index.umd.js"></script>
<!-- or -->
<script src="https://cdn.jsdelivr.net/npm/is-awaitable@latest/dist/index.umd.js"></script>

<script>
  const { isAwaitable } = window.IsAwaitable;

  async function foo() { return 'hello'; }
  function bar() { return 42; }

  console.log( isAwaitable(foo) ); // true
  console.log( isAwaitable(bar) ); // false
</script>

Usage

import { isAwaitable } from 'is-awaitable';

async function foo() { return 'ok'; }
console.log(isAwaitable(foo)); // true

const bar = async () => {};
console.log(isAwaitable(bar)); // true

async function* gen() { yield 1; }
console.log(isAwaitable(gen)); // true

function baz() { return 42; }
console.log(isAwaitable(baz)); // false

const returnsPromise = () => Promise.resolve('hi');
console.log(isAwaitable(returnsPromise)); // false

console.log(isAwaitable(null)); // false
console.log(isAwaitable(123)); // false

License

MIT License

Copyright (c) 2025 Ahmet Tinastepe

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.