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52 lines
1.8 KiB
52 lines
1.8 KiB
var startOfWeek = require('../start_of_week/index.js') |
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var MILLISECONDS_IN_MINUTE = 60000 |
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var MILLISECONDS_IN_WEEK = 604800000 |
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/** |
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* @category Week Helpers |
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* @summary Get the number of calendar weeks between the given dates. |
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* |
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* @description |
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* Get the number of calendar weeks between the given dates. |
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* |
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* @param {Date|String|Number} dateLeft - the later date |
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* @param {Date|String|Number} dateRight - the earlier date |
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* @param {Object} [options] - the object with options |
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* @param {Number} [options.weekStartsOn=0] - the index of the first day of the week (0 - Sunday) |
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* @returns {Number} the number of calendar weeks |
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* |
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* @example |
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* // How many calendar weeks are between 5 July 2014 and 20 July 2014? |
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* var result = differenceInCalendarWeeks( |
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* new Date(2014, 6, 20), |
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* new Date(2014, 6, 5) |
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* ) |
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* //=> 3 |
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* |
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* @example |
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* // If the week starts on Monday, |
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* // how many calendar weeks are between 5 July 2014 and 20 July 2014? |
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* var result = differenceInCalendarWeeks( |
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* new Date(2014, 6, 20), |
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* new Date(2014, 6, 5), |
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* {weekStartsOn: 1} |
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* ) |
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* //=> 2 |
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*/ |
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function differenceInCalendarWeeks (dirtyDateLeft, dirtyDateRight, dirtyOptions) { |
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var startOfWeekLeft = startOfWeek(dirtyDateLeft, dirtyOptions) |
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var startOfWeekRight = startOfWeek(dirtyDateRight, dirtyOptions) |
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var timestampLeft = startOfWeekLeft.getTime() - |
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startOfWeekLeft.getTimezoneOffset() * MILLISECONDS_IN_MINUTE |
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var timestampRight = startOfWeekRight.getTime() - |
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startOfWeekRight.getTimezoneOffset() * MILLISECONDS_IN_MINUTE |
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// Round the number of days 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((timestampLeft - timestampRight) / MILLISECONDS_IN_WEEK) |
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} |
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module.exports = differenceInCalendarWeeks
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