is-number 
Returns true if the value is a number. comprehensive tests.
Please consider following this project's author, Jon Schlinkert, and consider starring the project to show your ❤️ and support.
Install
Install with npm:
$ npm install --save is-number
Why is this needed?
This library provides a fast, simple way of checking whether a value is a number, whether defined as a string or number by the user.
It's easy to check for a number in JavaScript, all we need to do is typeof value === 'number'. But sometimes that's not enough. For example, typeof NaN returns number, and there are many use cases where it's possible or necessary for a numerical value to be defined as a string, like in parsers or regex matches where it's not possible for the value to be defined as a number.
Usage
To understand some of the rationale behind the decisions made in this library (and to learn about some oddities of number evaluation in JavaScript), see this gist.
const isNumber = require('is-number');
true
See the tests for more examples.
isNumber(5e3); // true
isNumber(0xff); // true
isNumber(-1.1); // true
isNumber(0); // true
isNumber(1); // true
isNumber(1.1); // true
isNumber(10); // true
isNumber(10.10); // true
isNumber(100); // true
isNumber('-1.1'); // true
isNumber('0'); // true
isNumber('012'); // true
isNumber('0xff'); // true
isNumber('1'); // true
isNumber('1.1'); // true
isNumber('10'); // true
isNumber('10.10'); // true
isNumber('100'); // true
isNumber('5e3'); // true
isNumber(parseInt('012')); // true
isNumber(parseFloat('012')); // true
False
See the tests for more examples.
isNumber('foo'); // false
isNumber([1]); // false
isNumber([]); // false
isNumber(function () {}); // false
isNumber(Infinity); // false
isNumber(NaN); // false
isNumber(new Buffer('abc')); // false
isNumber(null); // false
isNumber(undefined); // false
isNumber({abc: 'abc'}); // false
Release history
6.0.0
- optimizations, thanks to @benaadams.
5.0.0
Breaking changes
- removed support for
instanceof Numberandinstanceof String
About
Contributing
Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.
Running Tests
Running and reviewing unit tests is a great way to get familiarized with a library and its API. You can install dependencies and run tests with the following command:
$ npm install && npm test
Building docs
(This project's readme.md is generated by verb, please don't edit the readme directly. Any changes to the readme must be made in the .verb.md readme template.)
To generate the readme, run the following command:
$ npm install -g verbose/verb#dev verb-generate-readme && verb
Related projects
You might also be interested in these projects:
- is-plain-object: Returns true if an object was created by the
Objectconstructor. | homepage - is-primitive: Returns
trueif the value is a primitive. | homepage - isobject: Returns true if the value is an object and not an array or null. | homepage
- kind-of: Get the native type of a value. | homepage
Contributors
| Commits | Contributor |
|---|---|
| 47 | jonschlinkert |
| 5 | charlike-old |
| 1 | benaadams |
| 1 | realityking |
Author
Jon Schlinkert
License
Copyright © 2018, Jon Schlinkert. Released under the MIT License.
This file was generated by verb-generate-readme, v0.6.0, on March 31, 2018.