is-number

Returns true if the value is a finite number.

Please consider following this project's author, Jon Schlinkert, and consider starring the project to show your :heart: and support.

Install

Install with npm:

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 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 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: Returns true if an object was created by the Object constructor. | homepage
is-primitive: Returns true if 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 | | --- | --- | | 49 | jonschlinkert | | 5 | charlike-old | | 1 | benaadams | | 1 | realityking |

Author

Jon Schlinkert

License

This file was generated by verb-generate-readme, v0.6.0, on June 15, 2018.