javascript 한달전 후 날짜구하기

//일정목록

        if( empty(currentDate) ) {

            currentDate = getTodayYMD();

        }

//이전 버튼

        $('button[id=preBtn]').on('click', function(){

            /*한달전 날짜 구하기*/

            currentDate = getPreMonth(currentDate.substr(0,4),currentDate.substr(4,2),currentDate.substr(6,2));

            var calendarEl1 = document.getElementById('yearVal');

            $(calendarEl1).empty()[0].innerHTML = "<span>"+currentDate.substr(0,4)+"&nbsp;&nbsp;년</span><strong>"+currentDate.substr(4,2)+"</strong>월</p>";

            schdMngConstPlanDtl( currentDate, getlastDay(currentDate) );

        });

       

        //다음 버튼

        $('button[id=postBtn]').on('click', function(){

            /*한달후 날짜 구하기*/

            currentDate = getPostMonth(currentDate.substr(0,4),currentDate.substr(4,2),currentDate.substr(6,2));

            var calendarEl1 = document.getElementById('yearVal');

            $(calendarEl1).empty()[0].innerHTML = "<span>"+currentDate.substr(0,4)+"&nbsp;&nbsp;년</span><strong>"+currentDate.substr(4,2)+"</strong>월</p>";

            schdMngConstPlanDtl( currentDate, getlastDay(currentDate) );

        });

       

    /*한달전 날짜 구하기*/

    function getPreMonth(yyyy,mm,dd) {

        var now = new Date(yyyy,(mm-1),dd);

        var preDay = new Date( now.setMonth( now.getMonth() -1 ) );

        return getTodayYMD(preDay.getFullYear(),preDay.getMonth()+1,'01');

    }

    /*한달후 날짜 구하기*/

    function getPostMonth(yyyy,mm,dd) {

        var now = new Date(yyyy,(mm-1),dd);

        var postDay = new Date( now.setMonth( now.getMonth() +1 ) );

        return getTodayYMD(postDay.getFullYear(),postDay.getMonth()+1,'01');

    }

    /* 해당달의 마지막 날짜 구하기 */

    function getlastDay(source) {

        source = source.replace(/\D/ig, "");

        if (isNaN(source) || source.length < 6) {

            return "";

        }

        var year  = source.substring(0, 4);

        var month = source.substring(4, 6);

        var newDate  = new Date(year, month, 0);

        var newYear  = newDate.getFullYear();

        var newMonth = newDate.getMonth()+1;

        var newDay   = newDate.getDate();

        console.log(newMonth);

        if (newMonth.toString().length < 2) newMonth = "0" + newMonth;

        if (newDay.toString().length < 2) newDay = "0" + newDay;

        return newYear.toString() + newMonth.toString() + newDay.toString();

       

    }

 

참조 :  [JavaScript] 한달 전/후 날짜 구하기 (tistory.com)

[JavaScript] 한달 전/후 날짜 구하기