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add
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var isNumber = require('./isNumber');
/**
* Checks if `value` is `NaN`.
*
* **Note:** This method is based on
* [`Number.isNaN`](https://mdn.io/Number/isNaN) and is not the same as
* global [`isNaN`](https://mdn.io/isNaN) which returns `true` for
* `undefined` and other non-number values.
*
* @static
* @memberOf _
* @since 0.1.0
* @category Lang
* @param {*} value The value to check.
* @returns {boolean} Returns `true` if `value` is `NaN`, else `false`.
* @example
*
* _.isNaN(NaN);
* // => true
*
* _.isNaN(new Number(NaN));
* // => true
*
* isNaN(undefined);
* // => true
*
* _.isNaN(undefined);
* // => false
*/
function isNaN(value) {
// An `NaN` primitive is the only value that is not equal to itself.
// Perform the `toStringTag` check first to avoid errors with some
// ActiveX objects in IE.
return isNumber(value) && value != +value;
}
module.exports = isNaN;
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