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 王天杨
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import { toDate } from "./toDate.mjs";
/**
* @name startOfDecade
* @category Decade Helpers
* @summary Return the start of a decade for the given date.
*
* @description
* Return the start of a decade for the given date.
*
* @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
*
* @param date - The original date
*
* @returns The start of a decade
*
* @example
* // The start of a decade for 21 October 2015 00:00:00:
* const result = startOfDecade(new Date(2015, 9, 21, 00, 00, 00))
* //=> Jan 01 2010 00:00:00
*/
export function startOfDecade(date) {
// TODO: Switch to more technical definition in of decades that start with 1
// end with 0. I.e. 2001-2010 instead of current 2000-2009. It's a breaking
// change, so it can only be done in 4.0.
const _date = toDate(date);
const year = _date.getFullYear();
const decade = Math.floor(year / 10) * 10;
_date.setFullYear(decade, 0, 1);
_date.setHours(0, 0, 0, 0);
return _date;
}
// Fallback for modularized imports:
export default startOfDecade;
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