56 lines
2.0 KiB
JavaScript
56 lines
2.0 KiB
JavaScript
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"use strict";
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports.default = differenceInYears;
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var _index = _interopRequireDefault(require("../toDate/index.js"));
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var _index2 = _interopRequireDefault(require("../differenceInCalendarYears/index.js"));
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var _index3 = _interopRequireDefault(require("../compareAsc/index.js"));
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function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
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/**
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* @name differenceInYears
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* @category Year Helpers
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* @summary Get the number of full years between the given dates.
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*
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* @description
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* Get the number of full years between the given dates.
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*
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* ### v2.0.0 breaking changes:
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*
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* - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
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*
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* @param {Date|Number} dateLeft - the later date
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* @param {Date|Number} dateRight - the earlier date
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* @returns {Number} the number of full years
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* @throws {TypeError} 2 arguments required
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*
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* @example
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* // How many full years are between 31 December 2013 and 11 February 2015?
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* var result = differenceInYears(new Date(2015, 1, 11), new Date(2013, 11, 31))
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* //=> 1
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*/
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function differenceInYears(dirtyDateLeft, dirtyDateRight) {
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if (arguments.length < 2) {
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throw new TypeError('2 arguments required, but only ' + arguments.length + ' present');
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}
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var dateLeft = (0, _index.default)(dirtyDateLeft);
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var dateRight = (0, _index.default)(dirtyDateRight);
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var sign = (0, _index3.default)(dateLeft, dateRight);
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var difference = Math.abs((0, _index2.default)(dateLeft, dateRight));
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dateLeft.setFullYear(dateLeft.getFullYear() - sign * difference); // Math.abs(diff in full years - diff in calendar years) === 1 if last calendar year is not full
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// If so, result must be decreased by 1 in absolute value
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var isLastYearNotFull = (0, _index3.default)(dateLeft, dateRight) === -sign;
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var result = sign * (difference - isLastYearNotFull); // Prevent negative zero
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return result === 0 ? 0 : result;
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}
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module.exports = exports.default;
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