写了个JavaScript版的DateAdd、DateDiff、IsDate函数，大家评评!

需要说明的是，JavaScript中IsDate的参数必须为字符串，且支持6种不同的格式"yyyy-mm-dd || yyyy/mm/dd || dd-mm-yyyy || dd/mm/yyyy || mm-dd-yyyy || mm/dd/yyyy"，之所以不能使用日期作为参数是因为JavaScript根本没有不正确的日期，比如 new Date(2008,01,30)，构造函数会自动将它转换成正确的日期2008-03-01。


1.DateAdd函数：

<script language="javascript"> 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)); } } alert(DateAdd("s",1,new Date())); </script> [提示：你可先修改部分代码，再按运行]

2.DateDiff函数：

<script language="javascript"> 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); } } alert(DateDiff("d",new Date(2008,03,01),new Date(2008,03,20))); </script> [提示：你可先修改部分代码，再按运行]

3.IsDate函数：

<script language="javascript"> function IsDate(dateval){ var arr = new Array(); if(dateval.indexOf("-") != -1){ arr = dateval.toString().split("-"); }else if(dateval.indexOf("/") != -1){ arr = dateval.toString().split("/"); }else{ return false; } //yyyy-mm-dd || yyyy/mm/dd if(arr[0].length==4){ var date = new Date(arr[0],arr[1]-1,arr[2]); if(date.getFullYear()==arr[0] && date.getMonth()==arr[1]-1 && date.getDate()==arr[2]){ return true; } } //dd-mm-yyyy || dd/mm/yyyy if(arr[2].length==4){ var date = new Date(arr[2],arr[1]-1,arr[0]); if(date.getFullYear()==arr[2] && date.getMonth()==arr[1]-1 && date.getDate()==arr[0]){ return true; } } //mm-dd-yyyy || mm/dd/yyyy if(arr[2].length==4){ var date = new Date(arr[2],arr[0]-1,arr[1]); if(date.getFullYear()==arr[2] && date.getMonth()==arr[0]-1 && date.getDate()==arr[1]){ return true; } } return false; } alert(IsDate("2008-02-28")); alert(IsDate("02/30/2008")); </script> [提示：你可先修改部分代码，再按运行]