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