fast-isnumeric/index.js

The fast way to check if a JS object is numeric

/**
 * inspired by is-number <https://github.com/jonschlinkert/is-number>
 * but significantly simplified and sped up by ignoring number and string constructors
 * ie these return false:
 *   new Number(1)
 *   new String('1')
 */

'use strict';

var allBlankCharCodes = require('is-string-blank');

module.exports = function(n) {
    var type = typeof n;
    if(type === 'string') {
        var original = n;
        n = +n;
        // whitespace strings cast to zero - filter them out
        if(n===0 && allBlankCharCodes(original)) return false;
    }
    else if(type !== 'number') return false;

    return n - n < 1;
};