43 lines
1.6 KiB
JavaScript
43 lines
1.6 KiB
JavaScript
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import toInteger from '../_lib/toInteger/index.js';
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import toDate from '../toDate/index.js';
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import getDaysInMonth from '../getDaysInMonth/index.js';
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/**
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* @name addMonths
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* @category Month Helpers
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* @summary Add the specified number of months to the given date.
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*
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* @description
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* Add the specified number of months to the given date.
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*
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* ### v2.0.0 breaking changes:
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*
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* - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
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*
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* @param {Date|Number} date - the date to be changed
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* @param {Number} amount - the amount of months to be added
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* @returns {Date} the new date with the months added
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* @throws {TypeError} 2 arguments required
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*
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* @example
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* // Add 5 months to 1 September 2014:
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* var result = addMonths(new Date(2014, 8, 1), 5)
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* //=> Sun Feb 01 2015 00:00:00
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*/
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export default function addMonths(dirtyDate, dirtyAmount) {
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if (arguments.length < 2) {
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throw new TypeError('2 arguments required, but only ' + arguments.length + ' present');
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}
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var date = toDate(dirtyDate);
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var amount = toInteger(dirtyAmount);
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var desiredMonth = date.getMonth() + amount;
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var dateWithDesiredMonth = new Date(0);
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dateWithDesiredMonth.setFullYear(date.getFullYear(), desiredMonth, 1);
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dateWithDesiredMonth.setHours(0, 0, 0, 0);
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var daysInMonth = getDaysInMonth(dateWithDesiredMonth); // Set the last day of the new month
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// if the original date was the last day of the longer month
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date.setMonth(desiredMonth, Math.min(daysInMonth, date.getDate()));
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return date;
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}
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