is-extendable NPM version

Returns true if a value is any of the object types: array, regexp, plain object, function or date. This is useful for determining if a value can be extended, e.g. “can the value have keys?”


Install with npm

$ npm i is-extendable --save


var isExtendable = require('is-extendable');

Returns true if the value is any of the following:


All objects in JavaScript can have keys, but it’s a pain to check for this, since we ether need to verify that the value is not null or undefined and:

Also note that an extendable object is not the same as an extensible object, which is one that (in es6) is not sealed, frozen, or marked as non-extensible using preventExtensions.

Running tests

Install dev dependencies:

$ npm i -d && npm test


Pull requests and stars are always welcome. For bugs and feature requests, please create an issue


Jon Schlinkert


Copyright © 2015 Jon Schlinkert Released under the MIT license.

This file was generated by verb-cli on July 04, 2015.