is-number

What is is-number?

The is-number npm package is a simple utility for checking if a value is a number. It works with various types of numeric representations, including strings that can be coerced to numbers, and provides a straightforward API for determining if a value can be considered a number in JavaScript.

What are is-number's main functionalities?

Check if a value is a number

This feature allows you to check if a value is a number, including numeric strings.

const isNumber = require('is-number');

console.log(isNumber(5)); // true
console.log(isNumber('5')); // true
console.log(isNumber('five')); // false

Check if a value is not a number

This feature allows you to check if a value is not a number, including strings that cannot be coerced to numbers and other non-numeric types.

const isNumber = require('is-number');

console.log(isNumber('foo')); // false
console.log(isNumber([1, 2, 3])); // false

Check if a value is a finite number

This feature allows you to check if a value is a finite number, excluding Infinity, -Infinity, and NaN.

const isNumber = require('is-number');

console.log(isNumber(Infinity)); // false
console.log(isNumber(-Infinity)); // false
console.log(isNumber(NaN)); // false

Other packages similar to is-number

isnumeric

The isnumeric package offers similar functionality to is-number by checking if a value is numeric. It is similar in its simplicity and direct approach.

numerable

The numerable package is a more comprehensive library for number validation and formatting. It provides additional functionality compared to is-number, such as parsing and formatting numbers with localization support.

validate.io-number-primitive

This package is part of the validate.io suite and checks if a value is a number primitive. It is more strict than is-number as it does not consider numeric strings to be numbers.

README

is-number

Is the value a number? Has extensive tests.

Install

Install with npm:

npm i is-number --save-dev

Run tests

npm test

Usage

var isNumber = require('is-number');

true

isNumber(5e3);

isNumber(0xff);

isNumber(-1.1);
isNumber(0);
isNumber(1);
isNumber(1.1);
isNumber(10);
isNumber(10.10);
isNumber(100);

isNumber('-1.1');
isNumber('0');
isNumber('012');
isNumber('0xff');
isNumber('1');
isNumber('1.1');
isNumber('10');
isNumber('10.10');
isNumber('100');
isNumber('5e3');

isNumber(parseInt('012'));
isNumber(parseFloat('012'));

isNumber(Infinity);
isNumber('Infinity');

If you want Infinity to be false, just do:

var isNumber = require('is-number');

function isNum(val) {
  return isNumber(val) && isFinite(val);
}

false

isNumber('3abc');
isNumber('abc');
isNumber('abc3');
isNumber('null');
isNumber('undefined');
isNumber([1, 2, 3]);
isNumber(function () {});
isNumber(new Buffer('abc'));
isNumber(null);
isNumber(undefined);
isNumber({abc: 'abc'});
isNumber({});
isNumber([]);

Notes

Instead of using isFinite(), you can also achieve similar results by using something like ((+n+1) / (+n+1) === 1)), but this alone allows values like null to pass as numbers (in JavaScript, the leading + coerces the value to a number, see this gist for some oddities).

Author

Jon Schlinkert

• github/jonschlinkert
• twitter/jonschlinkert

License

Copyright (c) 2014 Jon Schlinkert, contributors.
Released under the MIT license

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This file was generated by verb-cli on September 21, 2014.