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 ❤️ and support.
Install
Install with npm:
$ 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:
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
const isNumber = require('is-number');
See the tests for more examples.
true
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:
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
.isFiniteif 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 Numberandinstanceof 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.
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 |
|---|---|
| 49 | 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 June 15, 2018.