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import toDate from "../toDate/index.js";
import requiredArgs from "../_lib/requiredArgs/index.js";
/**
* @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.
*
* @param {Date|Number} date - the original date
* @returns {Date} the start of a decade
* @throws {TypeError} 1 argument required
*
* @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 default function startOfDecade(dirtyDate) {
requiredArgs(1, arguments);
var date = toDate(dirtyDate);
var year = date.getFullYear();
var decade = Math.floor(year / 10) * 10;
date.setFullYear(decade, 0, 1);
date.setHours(0, 0, 0, 0);
return date;
}
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