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27 lines
922 B
27 lines
922 B
4 years ago
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var addISOYears = require('../add_iso_years/index.js')
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/**
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* @category ISO Week-Numbering Year Helpers
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* @summary Subtract the specified number of ISO week-numbering years from the given date.
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*
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* @description
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* Subtract the specified number of ISO week-numbering years from 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|String|Number} date - the date to be changed
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* @param {Number} amount - the amount of ISO week-numbering years to be subtracted
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* @returns {Date} the new date with the ISO week-numbering years subtracted
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*
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* @example
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* // Subtract 5 ISO week-numbering years from 1 September 2014:
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* var result = subISOYears(new Date(2014, 8, 1), 5)
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* //=> Mon Aug 31 2009 00:00:00
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*/
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function subISOYears (dirtyDate, dirtyAmount) {
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var amount = Number(dirtyAmount)
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return addISOYears(dirtyDate, -amount)
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}
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module.exports = subISOYears
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