is-async-function

What is is-async-function?

The is-async-function npm package is designed to help developers determine if a given function is an asynchronous function. This can be particularly useful in scenarios where the behavior of code needs to be altered based on whether a function is asynchronous or not, such as in dynamic function execution, middleware handling, or in libraries that need to support both synchronous and asynchronous operations.

What are is-async-function's main functionalities?

Checking if a function is asynchronous

This feature allows you to check if a given function is an async function. The package exports a single function that takes one argument (the function to check) and returns a boolean indicating whether the function is asynchronous. This is useful for dynamically handling functions based on their nature.

const isAsyncFunction = require('is-async-function');

async function foo() {};
console.log(isAsyncFunction(foo)); // true

function bar() {};
console.log(isAsyncFunction(bar)); // false

Other packages similar to is-async-function

is-promise

The is-promise package checks if a value is a Promise, which is a related but different check compared to is-async-function. While is-async-function checks the nature of the function itself, is-promise checks the return value of a function to determine if it's a Promise. This distinction is crucial in understanding and handling asynchronous operations in JavaScript.

kind-of

kind-of is a more general utility for checking the type of a value in JavaScript, which includes support for identifying functions and promises among many other types. Compared to is-async-function, kind-of offers a broader range of type checks but does not specifically focus on distinguishing between synchronous and asynchronous functions. It's more versatile but less specialized.

README

is-async-function

Is this a native async function?

Example

var isAsyncFunction = require('is-async-function');
assert(!isAsyncFunction(function () {}));
assert(!isAsyncFunction(null));
assert(!isAsyncFunction(function* () { yield 42; return Infinity; }));
assert(isAsyncFunction(async function () {}));

Tests

Simply clone the repo, npm install, and run npm test

Changelog

v2.1.0 - 2025-01-02

Commits

• [meta] use npmignore to autogenerate an npmignore file b8d050b
• [actions] split out node 10-20, and 20+ 1c8cd4b
• [New] add types 5ba6244
• [Robustness] use call-bound, safe-regex-test 9379ecd
• [actions] update rebase action to use reusable workflow 81b54fb
• [Tests] use for-each ebdc486
• [Dev Deps] update @ljharb/eslint-config, auto-changelog, npmignore, tape 9eb494f
• [Dev Deps] update aud, tape ea43809
• [Refactor] use get-proto directly fc46390
• [Tests] replace aud with npm audit edb4afb
• [Deps] update has-tostringtag dc78cf5
• [Dev Deps] add missing peer dep a93d8ff