bc518174
 王天杨
提交两个项目文件
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"use strict";
exports.differenceInYears = differenceInYears;
var _index = require("./compareAsc.js");
var _index2 = require("./differenceInCalendarYears.js");
var _index3 = require("./toDate.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.
*
* @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
*
* @param dateLeft - The later date
* @param dateRight - The earlier date
*
* @returns The number of full years
*
* @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(dateLeft, dateRight) {
const _dateLeft = (0, _index3.toDate)(dateLeft);
const _dateRight = (0, _index3.toDate)(dateRight);
const sign = (0, _index.compareAsc)(_dateLeft, _dateRight);
const difference = Math.abs(
(0, _index2.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
const isLastYearNotFull =
(0, _index.compareAsc)(_dateLeft, _dateRight) === -sign;
const result = sign * (difference - +isLastYearNotFull);
// Prevent negative zero
return result === 0 ? 0 : result;
}
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