Returns true if a number or string value is a finite number. Useful for regex matches, parsing, user input, etc.
npm install 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 with npm:
``sh`
$ npm install --save is-number
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.
`js`
const isNumber = require('is-number');
See the tests for more examples.
`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
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
* 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.
* Optimizations, thanks to @benaadams.
Breaking changes
* removed support for instanceof Number and instanceof String
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'
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:
sh
$ 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:
sh
$ npm install -g verbose/verb#dev verb-generate-readme && verb
`$3
You might also be interested in these projects:
* is-plain-object: Returns true if an object was created by the
constructor. | Object constructor."" class="text-primary hover:underline" target="_blank" rel="noopener noreferrer">homepage
* is-primitive: Returns true if the value is a primitive. | true` if the value is a primitive. "" class="text-primary hover:underline" target="_blank" rel="noopener noreferrer">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$3
| Commits | Contributor |
| --- | --- |
| 49 | jonschlinkert |
| 5 | charlike-old |
| 1 | benaadams |
| 1 | realityking |
$3
Jon Schlinkert
* LinkedIn Profile
* GitHub Profile
* Twitter Profile
$3
Copyright © 2018, Jon Schlinkert.
Released under the MIT License.
*
_This file was generated by verb-generate-readme, v0.6.0, on June 15, 2018._