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
v1.2.5 - 2022-09-11
5bb4b32eccheck command b9bd597npmignore to autogenerate an npmignore file 3192d38tryFunctionObject even in pre-toStringTag browsers 3076ea2eslint, @ljharb/eslint-config, available-typed-arrays, object-inspect, safe-publish-latest, tape 8986746auto-changelog 7dda9d0document.all da90b2bc8f847ceslint, @ljharb/eslint-config, aud, object-inspect, tape 899ae00eslint, @ljharb/eslint-config, es-value-fixtures, object-inspect, tape 344e913737dce5680a883has-tostringtag approach to behave correctly in the presence of symbol shamsprepublishOnly script for npm 7+node/install instead of node/run; use codecov actionnyc on all tests; use tape runneravailable-typed-arrays, for-each, has-symbols, object-inspectavailable-typed-arrays, eslint, @ljharb/eslint-config, aud, object-inspect, tapedocument.all is callable (do not use document.all!)eslint, @ljharb/eslint-config, aud, tapepull_request_target eventeslinteslint, @ljharb/eslint-configReflect.apply‑based callability detectionaud on prod depseslint, @ljharb/eslint-config, tape, make-arrow-function, make-generator-function; add aud, safe-publish-latest, make-async-functionfunding field; add FUNDING.ymleslint, @ljharb/eslint-config, semver, tape, covert, rimrafeccheck over editorconfig-toolsnpx aud instead of nsp or npm audit with hoopsjscsclass and arrow function detection (#30, #31)node v5.7, v4.3eslint v2, @ljharb/eslint-config, jscsnode v5.3parallelshell, run both --es-staging and stock tests at oncetape, jscs, nsp, eslint, @ljharb/eslint-configisNonES6ClassFn into isES6ClassFntape, eslint, @ljharb/eslint-config, jscs, nsp, semvernode v5.1typeof objectio.js v3.3, node v4.1eslint, editorconfig-tools, nsp, tape, semver, jscs, covert, make-arrow-functionReadme
Is this JS value callable? Works with Functions and GeneratorFunctions, despite ES6 @@toStringTag.
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 30,480,544 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.
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