# is-number
> Returns true if a number or string value is a finite number. Useful for regex matches, parsing, user input, etc.
Latest version **7.0.0** (published 2018-07-04) · MIT license · 0 weekly downloads
> **Better alternative:** Use typeof v === "number" || (typeof v === "string" && Number.isFinite(+v)) — Consider using a lighter alternative
## Install
```sh
npm install is-number
pnpm add is-number
yarn add is-number
bun add is-number
```
## Health
**Score 23/100 (F)** — status: abandoned.
Positive: has types package; no vulnerabilities; high quality score.
Warnings: low downloads; no esm support.
Negative: abandoned; low maintenance score.
## Facts
| | |
|---|---|
| Version | 7.0.0 |
| Published | 2018-07-04 |
| First published | 2014-09-22 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | separate (@types/is-number) |
| Module format | CommonJS |
| Node | >=0.12.0 |
| Dependencies | 0 |
| Unpacked size | 9.4 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 284 |
| Author | Jon Schlinkert |
| Maintainers | doowb, jonschlinkert, realityking |
| Keywords | cast, check, coerce, coercion, finite, integer, is, isnan, is-nan, is-num, is-number, isnumber, isfinite, istype, kind, math, nan, num, number, numeric, parseFloat, parseInt, test, type, typeof, value |
## Links
- npm: https://www.npmjs.com/package/is-number
- Repository: https://github.com/jonschlinkert/is-number
- Issues: https://github.com/jonschlinkert/is-number/issues
- npm.io page: https://npm.io/package/is-number
## Alternatives
- [memory-cache](https://npm.io/package/memory-cache.md) — 795.0K weekly downloads
- [@httptoolkit/proxy-agent](https://npm.io/package/@httptoolkit/proxy-agent.md) — 11.2K weekly downloads
- [express-cache-controller](https://npm.io/package/express-cache-controller.md) — 5.3K weekly downloads
- [http-cache-middleware](https://npm.io/package/http-cache-middleware.md) — 4.5K weekly downloads
- [cache2](https://npm.io/package/cache2.md) — 1.5K weekly downloads
## Recent versions
- 7.0.0 (latest) — 2018-07-04
- 6.0.0 — 2018-03-31
- 5.0.0 — 2018-01-29
- 4.0.0 — 2017-10-17
- 3.0.0 — 2016-09-11
- 2.1.0 — 2015-11-22
- 2.0.2 — 2015-05-03
- 2.0.1 — 2015-05-03
- 2.0.0 — 2015-05-02
- 1.1.2 — 2015-03-05
- 1.1.1 — 2015-03-05
- 1.1.0 — 2015-01-24
- 1.0.0 — 2015-01-24
- 0.1.1 — 2014-09-22
- 0.1.0 — 2014-09-22
## README
# is-number [](https://www.npmjs.com/package/is-number) [](https://npmjs.org/package/is-number) [](https://npmjs.org/package/is-number) [](https://travis-ci.org/jonschlinkert/is-number)
> Returns true if the value is a finite number.
Please consider following this project's author, [Jon Schlinkert](https://github.com/jonschlinkert), and consider starring the project to show your :heart: and support.
## Install
Install with [npm](https://www.npmjs.com/):
```sh
$ npm install --save is-number
```
## Why is this needed?
In JavaScript, it's not always as straightforward as it should be to reliably check if a value is a number. It's common for devs to use `+`, `-`, or `Number()` to cast a string value to a number (for example, when values are returned from user input, regex matches, parsers, etc). But there are many non-intuitive edge cases that yield unexpected results:
```js
console.log(+[]); //=> 0
console.log(+''); //=> 0
console.log(+' '); //=> 0
console.log(typeof NaN); //=> 'number'
```
This library offers a performant way to smooth out edge cases like these.
## Usage
```js
const isNumber = require('is-number');
```
See the [tests](./test.js) for more examples.
### true
```js
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
Everything else is false, as you would expect:
```js
isNumber(Infinity); // false
isNumber(NaN); // false
isNumber(null); // false
isNumber(undefined); // false
isNumber(''); // false
isNumber(' '); // false
isNumber('foo'); // false
isNumber([1]); // false
isNumber([]); // false
isNumber(function () {}); // false
isNumber({}); // false
```
## Release history
### 7.0.0
* Refactor. Now uses `.isFinite` if it exists.
* Performance is about the same as v6.0 when the value is a string or number. But it's now 3x-4x faster when the value is not a string or number.
### 6.0.0
* Optimizations, thanks to @benaadams.
### 5.0.0
**Breaking changes**
* removed support for `instanceof Number` and `instanceof String`
## Benchmarks
As with all benchmarks, take these with a grain of salt. See the [benchmarks](./benchmark/index.js) for more detail.
```
# all
v7.0 x 413,222 ops/sec ±2.02% (86 runs sampled)
v6.0 x 111,061 ops/sec ±1.29% (85 runs sampled)
parseFloat x 317,596 ops/sec ±1.36% (86 runs sampled)
fastest is 'v7.0'
# string
v7.0 x 3,054,496 ops/sec ±1.05% (89 runs sampled)
v6.0 x 2,957,781 ops/sec ±0.98% (88 runs sampled)
parseFloat x 3,071,060 ops/sec ±1.13% (88 runs sampled)
fastest is 'parseFloat,v7.0'
# number
v7.0 x 3,146,895 ops/sec ±0.89% (89 runs sampled)
v6.0 x 3,214,038 ops/sec ±1.07% (89 runs sampled)
parseFloat x 3,077,588 ops/sec ±1.07% (87 runs sampled)
fastest is 'v6.0'
```
## About
Contributing
Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
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:
```sh
$ npm install && npm test
```
Building docs
_(This project's readme.md is generated by [verb](https://github.com/verbose/verb-generate-readme), please don't edit the readme directly. Any changes to the readme must be made in the [.verb.md](.verb.md) readme template.)_
To generate the readme, run the following command:
```sh
$ npm install -g verbose/verb#dev verb-generate-readme && verb
```
### Related projects
You might also be interested in these projects:
* [is-plain-object](https://www.npmjs.com/package/is-plain-object): Returns true if an object was created by the `Object` constructor. | [homepage](https://github.com/jonschlinkert/is-plain-object "Returns true if an object was created by the `Object` constructor.")
* [is-primitive](https://www.npmjs.com/package/is-primitive): Returns `true` if the value is a primitive. | [homepage](https://github.com/jonschlinkert/is-primitive "Returns `true` if the value is a primitive. ")
* [isobject](https://www.npmjs.com/package/isobject): Returns true if the value is an object and not an array or null. | [homepage](https://github.com/jonschlinkert/isobject "Returns true if the value is an object and not an array or null.")
* [kind-of](https://www.npmjs.com/package/kind-of): Get the native type of a value. | [homepage](https://github.com/jonschlinkert/kind-of "Get the native type of a value.")
### Contributors
| **Commits** | **Contributor** |
| --- | --- |
| 49 | [jonschlinkert](https://github.com/jonschlinkert) |
| 5 | [charlike-old](https://github.com/charlike-old) |
| 1 | [benaadams](https://github.com/benaadams) |
| 1 | [realityking](https://github.com/realityking) |
### Author
**Jon Schlinkert**
* [LinkedIn Profile](https://linkedin.com/in/jonschlinkert)
* [GitHub Profile](https://github.com/jonschlinkert)
* [Twitter Profile](https://twitter.com/jonschlinkert)
### License
Copyright © 2018, [Jon Schlinkert](https://github.com/jonschlinkert).
Released under the [MIT License](LICENSE).
***
_This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.6.0, on June 15, 2018._
---
_Source: https://npm.io/package/is-number · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._