Formats numbers into groups of three digits separated with space, as used by NIST et. al.

See tests.

Install:

npm install --save nist-number

Use:

var nistNumber = require('nist-number')

nistNumber(123456) // = '123 456'
nistNumber(-123456) // = '-123 456'
nistNumber(-123456.7891 // = '-123 456.7891'

nistNumber(undefined) // = null
nistNumber(null) // = null
nistNumber('string is not a number') // = null
nistNumber({lol: 'object'}) // = null