JavaScript中中的dateadddatediff方法，很用的！
function DateAdd(interval,number,date){ switch(interval.toLowerCase()){ case "y": return new Date(date.setFullYear(date.getFullYear()+number)); case "m": return new Date(date.setMonth(date.getMonth()+number)); case "d": return new Date(date.setDate(date.getDate()+number)); case "w": return new Date(date.setDate(date.getDate()+7*number)); case "h": return new Date(date.setHours(date.getHours()+number)); case "n": return new Date(date.setMinutes(date.getMinutes()+number)); case "s": return new Date(date.setSeconds(date.getSeconds()+number)); case "l": return new Date(date.setMilliseconds(date.getMilliseconds()+number)); }}?

DateDiff函数：
程序代码

function DateDiff(interval,date1,date2){    var long = date2.getTime() - date1.getTime(); //相差毫秒    switch(interval.toLowerCase()){        case "y": return parseInt(date2.getFullYear() - date1.getFullYear());        case "m": return parseInt((date2.getFullYear() - date1.getFullYear())*12 + (date2.getMonth()-date1.getMonth()));        case "d": return parseInt(long/1000/60/60/24);        case "w": return parseInt(long/1000/60/60/24/7);        case "h": return parseInt(long/1000/60/60);        case "n": return parseInt(long/1000/60);        case "s": return parseInt(long/1000);        case "l": return parseInt(long);    }}