48 lines
1.6 KiB
JavaScript
48 lines
1.6 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 = getISOWeeksInYear;
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var _index = _interopRequireDefault(require("../startOfISOWeekYear/index.js"));
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var _index2 = _interopRequireDefault(require("../addWeeks/index.js"));
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var _index3 = _interopRequireDefault(require("../_lib/requiredArgs/index.js"));
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function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
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var MILLISECONDS_IN_WEEK = 604800000;
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/**
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* @name getISOWeeksInYear
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* @category ISO Week-Numbering Year Helpers
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* @summary Get the number of weeks in an ISO week-numbering year of the given date.
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*
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* @description
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* Get the number of weeks in an ISO week-numbering year of the given date.
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*
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* ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
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*
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* @param {Date|Number} date - the given date
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* @returns {Number} the number of ISO weeks in a year
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* @throws {TypeError} 1 argument required
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*
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* @example
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* // How many weeks are in ISO week-numbering year 2015?
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* const result = getISOWeeksInYear(new Date(2015, 1, 11))
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* //=> 53
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*/
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function getISOWeeksInYear(dirtyDate) {
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(0, _index3.default)(1, arguments);
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var thisYear = (0, _index.default)(dirtyDate);
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var nextYear = (0, _index.default)((0, _index2.default)(thisYear, 60));
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var diff = nextYear.valueOf() - thisYear.valueOf(); // Round the number of weeks to the nearest integer
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// because the number of milliseconds in a week is not constant
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// (e.g. it's different in the week of the daylight saving time clock shift)
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return Math.round(diff / MILLISECONDS_IN_WEEK);
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}
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module.exports = exports.default;
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