@stdlib/assert-is-function

What is @stdlib/assert-is-function?

@stdlib/assert-is-function is a utility package that provides functionality to check if a value is a function. This can be useful in various scenarios where type checking is necessary to ensure that a value can be invoked as a function.

What are @stdlib/assert-is-function's main functionalities?

Basic Function Check

This feature allows you to check if a given value is a function. It returns `true` if the value is a function and `false` otherwise.

const isFunction = require('@stdlib/assert-is-function');

console.log(isFunction(function() {})); // true
console.log(isFunction(null)); // false

Arrow Function Check

This feature supports checking if an arrow function is a function. It returns `true` for arrow functions.

const isFunction = require('@stdlib/assert-is-function');

console.log(isFunction(() => {})); // true

Class Method Check

This feature allows you to check if a class method is a function. It returns `true` for class methods.

const isFunction = require('@stdlib/assert-is-function');

class MyClass {
  myMethod() {}
}

console.log(isFunction(MyClass.prototype.myMethod)); // true

Other packages similar to @stdlib/assert-is-function

lodash.isfunction

lodash.isfunction is a utility function from the Lodash library that checks if a value is classified as a Function object. It is similar to @stdlib/assert-is-function but is part of the larger Lodash utility library, which provides a wide range of utility functions for common programming tasks.

is-function

is-function is a lightweight npm package that checks if a given value is a function. It is similar to @stdlib/assert-is-function in its core functionality but is a standalone package without additional utilities.

type-detect

type-detect is a library that provides type detection for JavaScript values. It can be used to check if a value is a function among other types. It offers more comprehensive type checking compared to @stdlib/assert-is-function, which focuses solely on function detection.

README

isFunction

Test if a value is a function.

Installation

npm install @stdlib/assert-is-function

Usage

var isFunction = require( '@stdlib/assert-is-function' );

isFunction( value )

Tests if a value is a function.

function beep() {
    console.log( 'beep' );
}

var bool = isFunction( beep );
// returns true

Examples

var isFunction = require( '@stdlib/assert-is-function' );

var bool = isFunction( function foo() {} );
// returns true

bool = isFunction( 'beep' );
// returns false

bool = isFunction( 5 );
// returns false

bool = isFunction( true );
// returns false

bool = isFunction( null );
// returns false

bool = isFunction( [] );
// returns false

bool = isFunction( {} );
// returns false

---

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

---

License

See LICENSE.

Copyright

Copyright © 2016-2021. The Stdlib Authors.