is-function
Advanced tools
Package description
The is-function npm package is a simple utility used for checking if a given value is a function. It is particularly useful in JavaScript environments where determining the type of an object can sometimes be less straightforward due to the dynamic nature of the language. This package provides a reliable way to ensure that a variable holds a function before attempting to invoke it, thus preventing runtime errors in code.
Function Type Checking
This feature allows developers to check if a variable is a function. It supports various types of functions including regular functions, async functions, and arrow functions. It returns true if the variable is a function and false otherwise. This is particularly useful for validating callbacks or any variable that is expected to be a function before invoking it.
const isFunction = require('is-function');
console.log(isFunction(function() {})); // true
console.log(isFunction(async () => {})); // true
console.log(isFunction(() => {})); // true
console.log(isFunction(class MyClass {})); // false
console.log(isFunction({})); // falselodash.isfunction is a part of the Lodash library, which is a broader utility library for JavaScript. While is-function focuses solely on checking if a value is a function, lodash.isfunction offers this functionality within the context of a larger set of utility functions. Lodash's isFunction method may be preferred in projects that already use Lodash for other utilities.
kind-of is a more general type checking library that can determine the type of a given value, including whether it is a function. Unlike is-function, which is specialized for function type checking, kind-of can be used to check a wide variety of types such as strings, numbers, objects, etc. This makes kind-of a more versatile choice if your project requires extensive type checking beyond just functions.
Readme
Is that thing a function? Use this module to find out.
Return true if fn is a function, otherwise false.
Because certain old browsers misreport the type of RegExp objects as functions.
I stole this from https://github.com/ljharb/object-keys
MIT
FAQs
is that thing a function? Use this module to find out
The npm package is-function receives a total of 3,082,341 weekly downloads. As such, is-function popularity was classified as popular.
We found that is-function demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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