JavaScript获取距离某天前或后的日期

/**

* param Date Object：Mon May 11 13:53:08 UTC+0800 2015

* n 自param 起向后多少天

* return Date Object：Mon May 11 13:53:08 UTC+0800 2015

*/

functiongetDateBeforeParamDate(param,n){

varresult =newDate();

if(param==null){

param = result;

}

if(n==null){

n=0;

}

param =newDate(param);

millSecond = param.valueOf();

millSecond = millSecond - n*24*3600*1000;

result =newDate(millSecond);

result = getTodayFormatea(result);

returnresult;

}

/**

* param Date对象：Mon May 11 13:53:08 UTC+0800 2015

* n 自param 向前多少天

* return Date Object：Mon May 11 13:53:08 UTC+0800 2015

*/

functiongetDateNextParamDate(param,n){

varresult =newDate();

if(param==null){

param = result;

}

if(n==null){

n=0;

}

param =newDate(param);

millSecond = param.valueOf();

millSecond = millSecond + n*24*3600*1000;

result =newDate(millSecond);

result = getTodayFormatea(result);

returnresult;

}