js 将指定日期增加n个月 或n年

示例

		   var bplimitdt = "${pd.LimitDT}";//选中系统到期时间
		   bplimitdt = new Date(bplimitdt);  //字符串转化成时间
		   var newDate = DateAdd("m ",3, bplimitdt);//bpmonth：新增三个月份
	   	   newDate = formatDate(newDate.getTime(),'YY-MM-DD hh:mm:ss');//格式化时间

1、日期增加运算

	function DateAdd(interval, number, date) {
	    switch (interval) {
	    case "y ": {
	        date.setFullYear(date.getFullYear() + number);
	        return date;
	        break;
	    }
	    case "q ": {
	        date.setMonth(date.getMonth() + number * 3);
	        return date;
	        break;
	    }
	    case "m ": {
	        date.setMonth(date.getMonth() + number);
	        return date;
	        break;
	    }
	    case "w ": {
	        date.setDate(date.getDate() + number * 7);
	        return date;
	        break;
	    }
	    case "d ": {
	        date.setDate(date.getDate() + number);
	        return date;
	        break;
	    }
	    case "h ": {
	        date.setHours(date.getHours() + number);
	        return date;
	        break;
	    }
	    case "m ": {
	        date.setMinutes(date.getMinutes() + number);
	        return date;
	        break;
	    }
	    case "s ": {
	        date.setSeconds(date.getSeconds() + number);
	        return date;
	        break;
	    }
	    default: {
	        date.setDate(d.getDate() + number);
	        return date;
	        break;
	    }
	    }
	}

2 、格式化时间

	function formatDate(time,format){
		var date = new Date(time);

		var year = date.getFullYear(),
			month = date.getMonth()+1,//月份是从0开始的
			day = date.getDate(),
			hour = date.getHours(),
			min = date.getMinutes(),
			sec = date.getSeconds();
		var preArr = Array.apply(null,Array(10)).map(function(elem, index) {
			return '0'+index;
		});////开个长度为10的数组 格式为 00 01 02 03

		var newTime = format.replace(/YY/g,year)
							.replace(/MM/g,preArr[month]||month)
							.replace(/DD/g,preArr[day]||day)
							.replace(/hh/g,preArr[hour]||hour)
							.replace(/mm/g,preArr[min]||min)
							.replace(/ss/g,preArr[sec]||sec);

		return newTime;			
	}