diff options
| -rw-r--r-- | src/lib.ts | 31 |
1 files changed, 20 insertions, 11 deletions
@@ -176,53 +176,61 @@ export function stepDate(date: HistDate, scale: number, {forward=true, count=1, count = -count; forward = !forward; } - for (let i = 0; i < count; i++){ + while (count > 0){ if (scale == DAY_SCALE){ if (forward && newDate.day < 28){ - newDate.day += 1; + let chg = Math.min(28 - newDate.day, count); + newDate.day += chg; + count -= chg; } else if (!forward && newDate.day > 1){ - newDate.day -= 1 + let chg = Math.min(newDate.day - 1, count); + newDate.day -= chg; + count -= chg; } else { let jdn = gregorianToJdn(newDate.year, newDate.month, newDate.day) jdn += forward ? 1 : -1; - const [year, month, day] = jdnToGregorian(jdn); - newDate.year = year; - newDate.month = month; - newDate.day = day; + [newDate.year, newDate.month, newDate.day] = jdnToGregorian(jdn); + count -= 1; } } else if (scale == MONTH_SCALE){ if (forward){ if (newDate.month < 12){ - newDate.month += 1; + let chg = Math.min(12 - newDate.month, count); + newDate.month += chg; + count -= chg; } else { newDate.year += 1; if (newDate.year == 0){ newDate.year = 1; } newDate.month = 1; + count -= 1; } } else { if (newDate.month > 1){ - newDate.month -= 1; + let chg = Math.min(newDate.month - 1, count); + newDate.month -= chg; + count -= chg; } else { newDate.year -= 1; if (newDate.year == 0){ newDate.year = -1; } newDate.month = 12; + count -= 1; } } } else { let newYear; if (forward){ - newYear = newDate.year + scale; + newYear = newDate.year + count*scale; if (newYear == 0){ // Account for there being no 0 CE newYear = 1; } else if (newDate.year == 1 && scale > 1){ newYear -= 1; } } else { - newYear = newDate.year - scale; + newYear = newDate.year - count*scale; if (newYear == 0 && scale > 1){ newYear = 1; } else if (newDate.year == 1){ @@ -230,6 +238,7 @@ export function stepDate(date: HistDate, scale: number, {forward=true, count=1, } } newDate.year = newYear; + count = 0; } } return newDate; |