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"use strict";
var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault").default;
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.default = differenceInYears;
var _index = _interopRequireDefault(require("../toDate/index.js"));
var _index2 = _interopRequireDefault(require("../differenceInCalendarYears/index.js"));
var _index3 = _interopRequireDefault(require("../compareAsc/index.js"));
var _index4 = _interopRequireDefault(require("../_lib/requiredArgs/index.js"));
/**
* @name differenceInYears
* @category Year Helpers
* @summary Get the number of full years between the given dates.
*
* @description
* Get the number of full years between the given dates.
*
* @param {Date|Number} dateLeft - the later date
* @param {Date|Number} dateRight - the earlier date
* @returns {Number} the number of full years
* @throws {TypeError} 2 arguments required
*
* @example
* // How many full years are between 31 December 2013 and 11 February 2015?
* const result = differenceInYears(new Date(2015, 1, 11), new Date(2013, 11, 31))
* //=> 1
*/
function differenceInYears(dirtyDateLeft, dirtyDateRight) {
(0, _index4.default)(2, arguments);
var dateLeft = (0, _index.default)(dirtyDateLeft);
var dateRight = (0, _index.default)(dirtyDateRight);
var sign = (0, _index3.default)(dateLeft, dateRight);
var difference = Math.abs((0, _index2.default)(dateLeft, dateRight));
// Set both dates to a valid leap year for accurate comparison when dealing
// with leap days
dateLeft.setFullYear(1584);
dateRight.setFullYear(1584);
// Math.abs(diff in full years - diff in calendar years) === 1 if last calendar year is not full
// If so, result must be decreased by 1 in absolute value
var isLastYearNotFull = (0, _index3.default)(dateLeft, dateRight) === -sign;
var result = sign * (difference - Number(isLastYearNotFull));
// Prevent negative zero
return result === 0 ? 0 : result;
}
module.exports = exports.default;
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