isNaN.js (911B)
1 var isNumber = require('./isNumber'); 2 3 /** 4 * Checks if `value` is `NaN`. 5 * 6 * **Note:** This method is based on 7 * [`Number.isNaN`](https://mdn.io/Number/isNaN) and is not the same as 8 * global [`isNaN`](https://mdn.io/isNaN) which returns `true` for 9 * `undefined` and other non-number values. 10 * 11 * @static 12 * @memberOf _ 13 * @since 0.1.0 14 * @category Lang 15 * @param {*} value The value to check. 16 * @returns {boolean} Returns `true` if `value` is `NaN`, else `false`. 17 * @example 18 * 19 * _.isNaN(NaN); 20 * // => true 21 * 22 * _.isNaN(new Number(NaN)); 23 * // => true 24 * 25 * isNaN(undefined); 26 * // => true 27 * 28 * _.isNaN(undefined); 29 * // => false 30 */ 31 function isNaN(value) { 32 // An `NaN` primitive is the only value that is not equal to itself. 33 // Perform the `toStringTag` check first to avoid errors with some 34 // ActiveX objects in IE. 35 return isNumber(value) && value != +value; 36 } 37 38 module.exports = isNaN;