29 lines
864 B
JavaScript
29 lines
864 B
JavaScript
import toDate from "../toDate/index.js";
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import requiredArgs from "../_lib/requiredArgs/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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* @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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* const 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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requiredArgs(1, arguments);
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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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} |