55 lines
1.7 KiB
JavaScript
55 lines
1.7 KiB
JavaScript
import toDate from '../toDate/index.js';
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/**
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* @name compareDesc
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* @category Common Helpers
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* @summary Compare the two dates reverse chronologically and return -1, 0 or 1.
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*
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* @description
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* Compare the two dates and return -1 if the first date is after the second,
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* 1 if the first date is before the second or 0 if dates are equal.
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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} dateLeft - the first date to compare
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* @param {Date|Number} dateRight - the second date to compare
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* @returns {Number} the result of the comparison
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* @throws {TypeError} 2 arguments required
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*
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* @example
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* // Compare 11 February 1987 and 10 July 1989 reverse chronologically:
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* var result = compareDesc(new Date(1987, 1, 11), new Date(1989, 6, 10))
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* //=> 1
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*
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* @example
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* // Sort the array of dates in reverse chronological order:
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* var result = [
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* new Date(1995, 6, 2),
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* new Date(1987, 1, 11),
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* new Date(1989, 6, 10)
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* ].sort(compareDesc)
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* //=> [
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* // Sun Jul 02 1995 00:00:00,
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* // Mon Jul 10 1989 00:00:00,
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* // Wed Feb 11 1987 00:00:00
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* // ]
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*/
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export default function compareDesc(dirtyDateLeft, dirtyDateRight) {
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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 dateLeft = toDate(dirtyDateLeft);
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var dateRight = toDate(dirtyDateRight);
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var diff = dateLeft.getTime() - dateRight.getTime();
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if (diff > 0) {
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return -1;
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} else if (diff < 0) {
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return 1; // Return 0 if diff is 0; return NaN if diff is NaN
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} else {
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return diff;
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}
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} |