es-toolkit/docs/reference/predicate/isFunction.md

isFunction

Checks if value is a function.

This function returns true if value is a function, and false otherwise.

This function can also serve as a type predicate in TypeScript, narrowing the type of the argument to a function.

Signature

function isFunction(value: unknown): value is (...args: never[]) => unknown;

Parameters

• value (unknown): The value to check if it is a function.

Returns

(value is (...args: never[]) => unknown): Returns true if the value is a function, otherwise false.

Examples

import { isFunction } from 'es-toolkit/predicate';

console.log(isFunction(Array.prototype.slice)); // true
console.log(isFunction(async function () {})); // true
console.log(isFunction(function* () {})); // true
console.log(isFunction(Proxy)); // true
console.log(isFunction(Int8Array)); // true