Current File : /var/www/html/node_modules/date-fns/esm/differenceInYears/index.js
import toDate from "../toDate/index.js";
import differenceInCalendarYears from "../differenceInCalendarYears/index.js";
import compareAsc from "../compareAsc/index.js";
import requiredArgs from "../_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.
*
* ### v2.0.0 breaking changes:
*
* - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
*
* @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
*/
export default function differenceInYears(dirtyDateLeft, dirtyDateRight) {
requiredArgs(2, arguments);
var dateLeft = toDate(dirtyDateLeft);
var dateRight = toDate(dirtyDateRight);
var sign = compareAsc(dateLeft, dateRight);
var difference = Math.abs(differenceInCalendarYears(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 = compareAsc(dateLeft, dateRight) === -sign;
var result = sign * (difference - Number(isLastYearNotFull)); // Prevent negative zero
return result === 0 ? 0 : result;
}
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