mout/date/diff.js

Modular Utilities

"use strict";
exports.__esModule = true;
var totalDaysInMonth_1 = require("./totalDaysInMonth");
var totalDaysInYear_1 = require("./totalDaysInYear");
var convert_1 = require("../time/convert");
/**
 * calculate the difference between dates (range)
 */
function diff(start, end, unitName) {
    // sort the dates to make it easier to process (specially year/month)
    if (start > end) {
        var swap = start;
        start = end;
        end = swap;
    }
    var output;
    if (unitName === 'month') {
        output = getMonthsDiff(start, end);
    }
    else if (unitName === 'year') {
        output = getYearsDiff(start, end);
    }
    else if (unitName != null) {
        if (unitName === 'day') {
            // ignore timezone difference because of daylight savings time
            start = toUtc(start);
            end = toUtc(end);
        }
        output = convert_1["default"](end - start, 'ms', unitName);
    }
    else {
        output = end - start;
    }
    return output;
}
function toUtc(d) {
    // we ignore timezone differences on purpose because of daylight
    // savings time, otherwise it would return fractional days/weeks even
    // if a full day elapsed. eg:
    // Wed Feb 12 2014 00:00:00 GMT-0200 (BRST)
    // Sun Feb 16 2014 00:00:00 GMT-0300 (BRT)
    // diff should be 4 days and not 4.041666666666667
    return Date.UTC(d.getUTCFullYear(), d.getUTCMonth(), d.getUTCDate(), d.getHours(), d.getMinutes(), d.getSeconds(), d.getMilliseconds());
}
function getMonthsDiff(start, end) {
    return (getElapsedMonths(start, end) +
        getElapsedYears(start, end) * 12 +
        getFractionalMonth(start, end));
}
function getYearsDiff(start, end) {
    var elapsedYears = getElapsedYears(start, end);
    return elapsedYears + getFractionalYear(start, end, elapsedYears);
}
function getElapsedMonths(start, end) {
    var monthDiff = end.getMonth() - start.getMonth();
    if (monthDiff < 0) {
        monthDiff += 12;
    }
    // less than a full month
    if (start.getDate() > end.getDate()) {
        monthDiff -= 1;
    }
    return monthDiff;
}
function getElapsedYears(start, end) {
    var yearDiff = end.getFullYear() - start.getFullYear();
    // less than a full year
    if (start.getMonth() > end.getMonth()) {
        yearDiff -= 1;
    }
    return yearDiff;
}
function getFractionalMonth(start, end) {
    var fractionalDiff = 0;
    var startDay = start.getDate();
    var endDay = end.getDate();
    if (startDay !== endDay) {
        var startTotalDays = totalDaysInMonth_1["default"](start);
        var endTotalDays = totalDaysInMonth_1["default"](end);
        var totalDays = void 0;
        var daysElapsed = void 0;
        if (startDay > endDay) {
            // eg: Jan 29 - Feb 27 (29 days elapsed but not a full month)
            var baseDay = startTotalDays - startDay;
            daysElapsed = endDay + baseDay;
            // total days should be relative to 1st day of next month if
            // startDay > endTotalDays
            totalDays = startDay > endTotalDays ? endTotalDays + baseDay + 1 : startDay + baseDay;
        }
        else {
            // fractional is only based on endMonth eg: Jan 12 - Feb 18
            // (6 fractional days, 28 days until next full month)
            daysElapsed = endDay - startDay;
            totalDays = endTotalDays;
        }
        fractionalDiff = daysElapsed / totalDays;
    }
    return fractionalDiff;
}
function getFractionalYear(start, end, elapsedYears) {
    var base = elapsedYears
        ? new Date(end.getFullYear(), start.getMonth(), start.getDate())
        : start;
    var elapsedDays = diff(base, end, 'day');
    return elapsedDays / totalDaysInYear_1["default"](end);
}
exports["default"] = diff;