引數說明：fromDate是"yyyy-MM-dd"的日期格式，為指定日期，例如‘2014-10-10’

                   dayInterval表示間隔天數，間隔天數大於0，則得到比指定日期大dayInterval天的日期，間隔天數小於0，則得到比指定日期小dayInterval天的日期

function getDateFromCurrentDate(fromDate,dayInterval){

var curDate = new Date(Date.parse(fromDate.replace(/-/g,"/")));
curDate.setDate(curDate.getDate()+dayInterval);
var year = curDate.getFullYear();
var month = (curDate.getMonth()+1)<10?"0"+(curDate.getMonth()+1):(curDate.getMonth()+1);
var day = curDate.getDate()<10?"0"+curDate.getDate():curDate.getDate();
return year+"-"+month+"-"+day;
};