[arzig]

I have not read the source but I had always assumed that this was the lovingly crafted effort of someone who is intimately familiar with the js standard making sure that some hypothetical expression like ![1] is neither odd nor even. Surely the idea that modulo is beyond developers is too horrifying to contemplate.

[umanwizard]

Here you go:

    /*!
     * is-odd <https://github.com/jonschlinkert/is-odd>
     *
     * Copyright (c) 2015-2017, Jon Schlinkert.
     * Released under the MIT License.
     */
    
    'use strict';
    
    const isNumber = require('is-number');
    
    module.exports = function isOdd(value) {
      const n = Math.abs(value);
      if (!isNumber(n)) {
        throw new TypeError('expected a number');
      }
      if (!Number.isInteger(n)) {
        throw new Error('expected an integer');
      }
      if (!Number.isSafeInteger(n)) {
        throw new Error('value exceeds maximum safe integer');
      }
      return (n % 2) === 1;
    };

It does some checking the `value` is an integer in the safe range, which doesn't even seem right to me. Why shouldn't you be able to call this on integers outside the save range?

[johnfn]

(10e15 + 1) % 2 === 0

[addaon]

All non-safe integers are even, yes?

[fifilura]

Sad but true. For JavaScript these kind of functions can actually be useful because of all the quirks. If that was the GPs hint then I can understand.