IsNumber

Well tested 'is number' checks, that can accept number-like strings, and non-finite values as desired.

There are a lot of is number tests out there. Many of them don't work quite right. Others use a different definition of is number than you might want. So after spending way too much time for such a simple thing, here are four checks:

|Function |number literals|number-like strings|Infinity and NaN|Infinity and NaN strings|other strings| |----------------|---------------|-------------------|----------------|------------------------|-------------| |isNumeric |true |true |true |true |false | |isNumber |true |false |true |false |false | |isFiniteNumeric |true |true |false |false |false | |isFiniteNumber |true |false |false |false |false |

Table of Contents

• Installation
• Getting Started
• API
  • isNumber
  • isNumeric
  • isFiniteNumber
  • isFiniteNumeric
• Credits
• Contributing
• Issues
• License

Installation

npm install --save @toolbuilder/isnumber

Getting Started

This is a dual package, so named exports are available for both CommonJS and ES modules.

import { isNumeric, isFiniteNumeric, isNumber, isFiniteNumber } from '@toolbuilder/isnumber'

console.log(isNumeric('1.234')) // true because it looks like a number
console.log(isFiniteNumeric(42.54)) // true
console.log(isNumber('1.234')) // false because it is a string
console.log(isFiniteNumber(-Infinity)) // false

API

API documentation follows.

isNumber

Test if n is a number.

Includes Infinities and NaN, does not include strings that look like numbers

Parameters:

• n any value to test

isNumber(1.23) // true
isNumber(Infinity) // true
isNumber(NaN) // true
isNumber('1.23') // false

Returns boolean true if is number, false otherwise

isNumeric

Test if n is a number, or string that parses to a number. Includes infinities and NaN.

Non-finite strings are: 'Infinity', '-Infinity', and 'NaN'.

Parameters:

• n any value to test

isNumeric(1.23) // true
isNumeric('Infinity') // true
isNumeric(NaN) // true
isNumeric('1.23') // true
isNumeric('hi') // false

Returns boolean true if is numeric, false otherwise

isFiniteNumber

Test if n is a finite number.

Does not include infinities, NaN, or strings that look like numbers.

Parameters:

• n any value to test

isFiniteNumber(1.23) // true
isFiniteNumber(Infinity) // false
isFiniteNumber(NaN) // false
isFiniteNumber('1.23') // false

Returns boolean true if is a finite number, false otherwise

isFiniteNumeric

Test if n is a finite number, or string that parses to a finite number.

Does not include infinities, NaN

Parameters:

• n any value to test

isFiniteNumeric(1.23) // true
isFiniteNumeric('Infinity') // false
isFiniteNumeric(NaN) // false
isFiniteNumeric('1.23') // true
isFiniteNumeric('hi') // false

Returns boolean true if is a finite number, false otherwise

Credits

The isFiniteNumeric implementation, and the most of the tests were copied from this site. I found these tests on Stack Overflow in an answer by 'CMS'. Thanks!

Contributing

Contributions are welcome. Please create a pull request.

• I use pnpm instead of npm.
• Run the unit tests with pnpm test
• Package verification requires pnpm to be installed globally.
  • npm install -g pnpm
  • pnpm install
  • pnpm build to build cjs, docs, and *.d.ts
  • pnpm run check:packfile to test against ES and CommonJS projects, as well as Electron
  • pnpm run check to validate the package is ready for commit

Issues

This project uses Github issues.

License

MIT