waterline
Version:
An ORM for Node.js and the Sails framework
45 lines (36 loc) • 1.79 kB
JavaScript
/**
* Module dependencies
*/
var lodash4IsSafeInteger = require('lodash.issafeinteger');
/**
* isSafeNaturalNumber()
*
* Determine whether this value is a safe, natural number:
* • `safe` | `<= Number.MAX_SAFE_INTEGER` (see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/MAX_SAFE_INTEGER)
* • `natural` | `> 0 && !== Infinity && !== NaN && Math.floor(x) === x` (positive, non-zero, finite, round number. In other words, no funny business -- aka "positive, non-zero integer")
* ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* @param {Ref} value
* ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* @returns {Boolean}
*/
module.exports = function isSafeNaturalNumber(value) {
// Return false for:
// • NaN
// • Infinity / -Infinity
// • 0 / -0
// • fractions
// • negative integers
// • and integers greater than `Number.MAX_SAFE_INTEGER`
//
// Otherwise, return true!
//
// > For more on `Number.isSafeInteger()`, check out MDN:
// > https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isSafeInteger
// Note that, eventually, we can just do:
// ```
// return Number.isSafeInteger(value) && value > 0;
// ```
// But for compatibility with legacy versions of Node.js, we do:
// (implementation borrowed from https://github.com/lodash/lodash/blob/4.17.2/lodash.js#L12094)
return lodash4IsSafeInteger(value) && value > 0;
};