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backend/node_modules/date-fns/differenceInCalendarISOWeeks/index.js

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+"use strict";
+
+var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault").default;
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = differenceInCalendarISOWeeks;
+var _index = _interopRequireDefault(require("../_lib/getTimezoneOffsetInMilliseconds/index.js"));
+var _index2 = _interopRequireDefault(require("../startOfISOWeek/index.js"));
+var _index3 = _interopRequireDefault(require("../_lib/requiredArgs/index.js"));
+var MILLISECONDS_IN_WEEK = 604800000;
+
+/**
+ * @name differenceInCalendarISOWeeks
+ * @category ISO Week Helpers
+ * @summary Get the number of calendar ISO weeks between the given dates.
+ *
+ * @description
+ * Get the number of calendar ISO weeks between the given dates.
+ *
+ * ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
+ *
+ * @param {Date|Number} dateLeft - the later date
+ * @param {Date|Number} dateRight - the earlier date
+ * @returns {Number} the number of calendar ISO weeks
+ * @throws {TypeError} 2 arguments required
+ *
+ * @example
+ * // How many calendar ISO weeks are between 6 July 2014 and 21 July 2014?
+ * const result = differenceInCalendarISOWeeks(
+ *   new Date(2014, 6, 21),
+ *   new Date(2014, 6, 6)
+ * )
+ * //=> 3
+ */
+function differenceInCalendarISOWeeks(dirtyDateLeft, dirtyDateRight) {
+  (0, _index3.default)(2, arguments);
+  var startOfISOWeekLeft = (0, _index2.default)(dirtyDateLeft);
+  var startOfISOWeekRight = (0, _index2.default)(dirtyDateRight);
+  var timestampLeft = startOfISOWeekLeft.getTime() - (0, _index.default)(startOfISOWeekLeft);
+  var timestampRight = startOfISOWeekRight.getTime() - (0, _index.default)(startOfISOWeekRight);
+
+  // Round the number of days 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((timestampLeft - timestampRight) / MILLISECONDS_IN_WEEK);
+}
+module.exports = exports.default;