index.js

'use strict';

var getDay = Date.prototype.getDay;
var tryDateObject = function tryDateGetDayCall(value) {
	try {
		getDay.call(value);
		return true;
	} catch (e) {
		return false;
	}
};

var toStr = Object.prototype.toString;
var dateClass = '[object Date]';
var hasToStringTag = typeof Symbol === 'function' && !!Symbol.toStringTag;

module.exports = function isDateObject(value) {
	if (typeof value !== 'object' || value === null) {
		return false;
	}
	return hasToStringTag ? tryDateObject(value) : toStr.call(value) === dateClass;
};