35 lines
1.1 KiB
JavaScript
35 lines
1.1 KiB
JavaScript
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import toDate from '../toDate/index.js';
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/**
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* @name startOfDecade
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* @category Decade Helpers
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* @summary Return the start of a decade for the given date.
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*
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* @description
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* Return the start of a decade for 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 original date
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* @returns {Date} the start of a decade
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* @throws {TypeError} 1 argument required
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*
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* @example
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* // The start of a decade for 21 October 2015 00:00:00:
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* var result = startOfDecade(new Date(2015, 9, 21, 00, 00, 00))
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* //=> Jan 01 2010 00:00:00
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*/
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export default function startOfDecade(dirtyDate) {
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if (arguments.length < 1) {
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throw new TypeError('1 argument required, but only ' + arguments.length + ' present');
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}
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var date = toDate(dirtyDate);
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var year = date.getFullYear();
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var decade = Math.floor(year / 10) * 10;
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date.setFullYear(decade, 0, 1);
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date.setHours(0, 0, 0, 0);
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return date;
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}
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