54 lines
2.0 KiB
JavaScript
54 lines
2.0 KiB
JavaScript
|
"use strict";
|
||
|
|
|
||
|
|
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"));
|
||
|
|
|
||
|
|
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @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;
|