日期加减

<script language="javascript">

/* 得到日期年月日等加数字后的日期 */

Date.prototype.dateAdd = function(interval,number)

{

var d = this;

var k={"y":"FullYear", "q":"Month", "m":"Month", "w":"Date", "d":"Date", "h":"Hours", "n":"Minutes", "s":"Seconds", "ms":"MilliSeconds"};

var n={"q":3, "w":7};

eval("d.set"+k[interval]+"(d.get"+k[interval]+"()+"+((n[interval]||1)*number)+")");

return d;

};

/* 计算两日期相差的日期年月日等 */

Date.prototype.dateDiff = function(interval,objDate)

{

var d=this, t=d.getTime(), t2=objDate.getTime(), i={};

i["y"]=objDate.getFullYear()-d.getFullYear();

i["q"]=i["y"]*4+Math.floor(objDate.getMonth()/4)-Math.floor(d.getMonth()/4);

i["m"]=i["y"]*12+objDate.getMonth()-d.getMonth();

i["ms"]=objDate.getTime()-d.getTime();

i["w"]=Math.floor((t2+345600000)/(604800000))-Math.floor((t+345600000)/(604800000));

i["d"]=Math.floor(t2/86400000)-Math.floor(t/86400000);

i["h"]=Math.floor(t2/3600000)-Math.floor(t/3600000);

i["n"]=Math.floor(t2/60000)-Math.floor(t/60000);

i["s"]=Math.floor(t2/1000)-Math.floor(t/1000);

return i[interval];

};



/*调用例子*/

window.onload = function(){

/*

interval:类型参数，可为："y":"FullYear", "q":"Month", "m":"Month", "w":"Date", "d":"Date", "h":"Hours", "n":"Minutes", "s":"Seconds", "ms":"MilliSeconds"

number:对应加上的数值

*/

var d1 = new Date();

//alert(d1.toLocaleString());

d1.dateAdd("d" ,1);

alert(d1.toLocaleString());/*加1年*/



/*

interval:类型参数，可为："y":"FullYear", "q":"Month", "m":"Month", "w":"Date", "d":"Date", "h":"Hours", "n":"Minutes", "s":"Seconds", "ms":"MilliSeconds"

objDate:日期对象

*/

var d2 = new Date();

//alert("相隔了"+ d2.dateDiff("y" ,d1) +"年");

};

</script>

<script>

var date = new Date(2009, 6, 1);

alert(date);

date.setDate(date.getDate() + 1);

alert(date);

</script>

var dt = new Date(2009,6,1); 

var dt1 = new Date(dt.getFullYear(), dt.getMonth(), dt.getDate()-1);

var dt2 = new Date(dt.getFullYear(), dt.getMonth(), dt.getDate()+1);

alert(dt1);

alert(dt2);