js實現日期年月日加減，自動處理閏年

使用js實現日期加減

使用js實現日期年月日的加減，自動處理閏年：

function setDateTest() {
	addOrReduceDate("D","2019-6-15 14:45:16","5");
}
// type:年、月或者日
// data:日期
// 加減量
function addOrReduceDate(type,date,num) {
	var nowDate = null;
	var strDate = "";
	num = parseInt(num); // 防止傳入字符串報錯
	var seperator1 = "-";
	var seperator2 = ":";
	if(date == "") {
		nowDate = new Date();
	} else {
		nowDate = new Date(date);
	}
	
	if(type==="Y"){
		nowDate.setFullYear(nowDate.getFullYear() + num);
	}
	if(type==="M"){
		nowDate.setMonth(nowDate.getMonth() + num);
	}
	if(type==="D"){
		nowDate.setDate(nowDate.getDate() + num);
	}
	if(type==="A"){
		nowDate.setFullYear(nowDate.getFullYear() + num);
		nowDate.setMonth(nowDate.getMonth() + num);
		nowDate.setDate(nowDate.getDate() + num);
	}
	var year = nowDate.getFullYear(); // 年
	var month = nowDate.getMonth() + 1; // 月
	strDate = nowDate.getDate(); //日
	var hours = nowDate.getHours(); // 時
	var minutes = nowDate.getMinutes(); // 分
	var seconds = nowDate.getSeconds(); // 秒
	if(month >= 1 && month <= 9) {
		month = "0" + month;
	}
	if(strDate >= 0 && strDate <= 9) {
		strDate = "0" + strDate;
	}
	if(seconds >= 0 && seconds <= 9) {
		seconds = "0" + seconds;
	}
	var dateStr = year + seperator1 + month + seperator1 + strDate + " " + hours + seperator2 + minutes + seperator2 + seconds;
	console.log(dateStr)
	return dateStr;
}