is-callable
Advanced tools
Package description
The is-callable npm package is used to determine if a value is callable, meaning it can be called as a function. This is useful for type-checking in JavaScript where the typeof operator can be insufficient for certain cases, such as distinguishing between callable and non-callable objects.
Check if a value is callable
This feature allows you to check if various types of values are callable, including regular functions, async functions, arrow functions, and classes. It also correctly identifies non-callable objects like regex literals and plain objects.
const isCallable = require('is-callable');
console.log(isCallable(function() {})); // true
console.log(isCallable(async function() {})); // true
console.log(isCallable(() => {})); // true
console.log(isCallable(class MyClass {})); // true
console.log(isCallable(/regex/)); // false
console.log(isCallable(null)); // false
console.log(isCallable({})); // falseThe is-function package is similar to is-callable in that it checks if a given value is a function. However, it may not handle all the cases that is-callable does, such as ES6 classes or callable objects.
Lodash provides a method called isFunction which is part of the larger lodash utility library. It is similar to is-callable but is part of a larger set of utility functions and may not distinguish between all types of callable entities as is-callable does.
Changelog
v1.2.6 - 2022-09-14
document.all in Firefox 3 and IE 6-8 015132a86981160442207a501141class constructor tests to fail in FF v45 - v54, which has undetectable classes b12e4a44b732ffdocument.all in Safari 4 3193735Readme
Is this JS value callable? Works with Functions and GeneratorFunctions, despite ES6 @@toStringTag.
Automatically tested in every minor version of node.
Manually tested in:
class, but Function.prototype.toString hides that progeny and makes them look like functions, so class constructors will be reported by this package as callable, when they are not in fact callable.class, but Function.prototype.toString hides that progeny and makes them look like functions, so class constructors will be reported by this package as callable, when they are not in fact callable.var isCallable = require('is-callable');
var assert = require('assert');
assert.notOk(isCallable(undefined));
assert.notOk(isCallable(null));
assert.notOk(isCallable(false));
assert.notOk(isCallable(true));
assert.notOk(isCallable([]));
assert.notOk(isCallable({}));
assert.notOk(isCallable(/a/g));
assert.notOk(isCallable(new RegExp('a', 'g')));
assert.notOk(isCallable(new Date()));
assert.notOk(isCallable(42));
assert.notOk(isCallable(NaN));
assert.notOk(isCallable(Infinity));
assert.notOk(isCallable(new Number(42)));
assert.notOk(isCallable('foo'));
assert.notOk(isCallable(Object('foo')));
assert.ok(isCallable(function () {}));
assert.ok(isCallable(function* () {}));
assert.ok(isCallable(x => x * x));
Install with
npm install is-callable
Simply clone the repo, npm install, and run npm test
FAQs
Is this JS value callable? Works with Functions and GeneratorFunctions, despite ES6 @@toStringTag.
The npm package is-callable receives a total of 30,518,161 weekly downloads. As such, is-callable popularity was classified as popular.
We found that is-callable 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.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Security News
Tea.xyz, a crypto project aimed at rewarding open source contributions, is once again facing backlash due to an influx of spam packages flooding public package registries.
Security News
As cyber threats become more autonomous, AI-powered defenses are crucial for businesses to stay ahead of attackers who can exploit software vulnerabilities at scale.
Security News
UnitedHealth Group disclosed that the ransomware attack on Change Healthcare compromised protected health information for millions in the U.S., with estimated costs to the company expected to reach $1 billion.