把周数转化为日期

Posted 2022-12-06 yang_chuanlong

function convertWeekNumberToFirstDate(sYear, sWeek, startFromFirstMonday)

    if (startFromFirstMonday == undefined) startFromFirstMonday = true;

    var weekIndex = 1;

    var year = parseInt(sYear);
    var week = parseInt(sWeek);

    var i = 1;
    var dFirstDate = new Date(year, 0, i);

    if (!startFromFirstMonday)
    
        if (weekIndex < week)
        
            weekIndex++;
        
        else
            return dFirstDate;
    

    if (dFirstDate.getDay() != 1)
    
        i += 7 - dFirstDate.getDay() + 1;
        dFirstDate.setFullYear(year, 0, i);
    

    if (weekIndex < week)
    
        i += 7*(week-weekIndex);
        dFirstDate.setFullYear(year, 0, i);
    

    return dFirstDate;