Javascript获取本周，本月，本季，本年，上月，上周，上季，去年，上二周，上二月

Javascript获取本周，本月，本季，本年，上月，上周，上季，去年，上二周，上二月的时间段

function dateChange(name){
var beginTimeObject = document.getElementById("beginTime");
var endTimeObject = document.getElementById("endTime");


var beginTime;
var endTime;
var now = new Date();
var month = now.getMonth();
var year = now.getFullYear();
var day = now.getDate();
var wday = now.getDay();


switch(name){
case "tweek": //本周
var day  = now.getDay();
now.setDate(now.getDate() - (day -1));
beginTime = formatDate(now);

now.setDate(now.getDate() + 6);
endTime = formatDate(now);
break;
case "tmonth":  //本月
now.setDate(1);
beginTime = formatDate(now);

var days = getDays(now);
now.setDate(days);
endTime = formatDate(now);
break;
case "tquarter":   //本季
var m = now.getMonth() + 1;
var q = parseInt((m + 2 ) / 3 ); //得到第几季
m = q * 3 - 2;  //得到季的首月份

now.setMonth(m-1);
now.setDate(1);
beginTime = formatDate(now);

now.setMonth(now.getMonth() + 3);
now.setDate(0);
endTime = formatDate(now);
break;
case "tyear":    //本年
now.setMonth(0);
now.setDate(1);
beginTime = formatDate(now);

now.setMonth(11);
now.setDate(31);
endTime = formatDate(now);        
break;
case "today":    //今天
beginTime = formatDate(now);
endTime = beginTime;
break;
case "pweek":    //上周
var day  = now.getDay();
now.setDate(now.getDate() - (day -1) - 7 );
beginTime = formatDate(now);

now.setDate(now.getDate() + 6);
endTime = formatDate(now);

break;
case "pmonth":    //上月
now.setDate(1);
now.setMonth(now.getMonth() -1 );
beginTime = formatDate(now);

var days = getDays(now);
now.setDate(days);
endTime = formatDate(now);
break;
case "pquarter":    //上季
var m = now.getMonth() + 1;
var q = parseInt((m + 2 ) / 3 ); //得到第几季
m = q * 3 - 2;  //得到季的首月份

m = m-3 ; //上季
now.setMonth(m-1);
now.setDate(1);
beginTime = formatDate(now);

now.setMonth(now.getMonth() + 3);
now.setDate(0);
endTime = formatDate(now);        
break;
case "pyear":    //去年
now.setFullYear(now.getFullYear() -1 );
now.setMonth(0);
now.setDate(1);
beginTime = formatDate(now);

now.setMonth(11);
now.setDate(31);
endTime = formatDate(now);            
break;
case "p2week":    //上二周
var day  = now.getDay();
now.setDate(now.getDate() - (day -1) - 7 *2);
beginTime = formatDate(now);

now.setDate(now.getDate() + 6 + 7);
endTime = formatDate(now);            
break;
case "p2month":    //上二月
now.setDate(1);
now.setMonth(now.getMonth() -1*2 );
beginTime = formatDate(now);

now.setMonth(now.getMonth() + 2);
now.setDate(0);
endTime = formatDate(now);
break;
case "customize":    //自定义
beginTime = "";
endTime = "";
break;
}

beginTimeObject.value = beginTime;
endTimeObject.value = endTime;
}

 引自：http://hi.baidu.com/xixitie/item/b3d98eeca9d9633987d9de66