如何在JavaScript中使用兩年的時間範圍內的月份範圍

Question

我希望根據用戶選擇的範圍獲得以前的月份範圍。例如，如果用戶選擇：July-2015至September-2015。我可以使用下面的對象獲取數字月份值。

var months = {January: 1, February: 2, March: 3, April: 4, May: 5, June: 6, July: 7, August: 8, September: 9, October: 10, November: 11, December: 12}; 

那麼我可以用這樣的邏輯來弄清楚之前的範圍 - http://jsfiddle.net/0cq5nprt/

var currStartMonth = 7, 
    currEndMonth = 9, 
    monthRange = (currEndMonth - currStartMonth) + 1, 
    prevStartMonth = currStartMonth - monthRange, 
    prevEndMonth = (prevStartMonth + monthRange) - 1; 

我遇到的問題是，當範圍是在兩年所以它就像跨度：December- 2014年至2015年1月。這裏應該是2014年10月至2014年11月。

希望我的問題很清楚。任何建議將非常有幫助！

Answer 1

我想你應該在你的計算中使用年份。像下面的東西。

var yearDiff = endYear - currentYear 
if yearDiff = 0 { 
    monthRange = (currEndMonth - currStartMonth) + 1, 
    prevStartMonth = currStartMonth - monthRange, 
    prevEndMonth = (prevStartMonth + monthRange) - 1; 
} else { 
    calcEndMonth = calcEndMonth + 12 
    monthRange = (calcEndMonth - currStartMonth) + 1, 
    prevStartMonth = curgstartmonth - monthRange, 
    prevEndMonth = (prevStartMonth + monthRange) - 1; 
    if prevEndMonth > 12 { 
     prevEndYear = curEndYear - 1 
     prevEndMonth = prevEndMonth - 12 
    } 
} 

考慮您的示例12 - 2014年一月至2015年

var yearDiff = endYear - currentYear 
// yearDiff = 2015 - 2014 = 1 

{ 
    calcEndMonth = calcEndMonth + 12 
    //calcEndMonth = 1 + 12 = 13 

    monthRange = (calcEndMonth - currStartMonth) + 1, 
    //monthRange = (13 - 12) + 1 = 2 

    prevStartMonth = curStartmonth - monthRange, 
    //prevStartMonth = 12 (December) - 2 = 10(October) 

    prevEndMonth = (prevStartMonth + monthRange) - 1; 
    //prevEndMonth = (10 + 2) - 1 = 11(November) 

    if prevEndMonth > 12 { 
     prevEndYear = curEndYear - 1 
     prevEndMonth = prevEndMonth - 12 

    }