js把String类转换为日期类并计算

//计算日期加法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; ???} ???}}

//把String类的日期转换为Date类var date = new Date(2017-09-14 00:00:00.000);//然后计算var nextDate = DateAdd("y",3,date)