String.prototype.trim = function()
{
	return this.replace(/(^\s*)|(\s*$)/g, "");
}

function changeToday(queryform)
{
	// 当天
	var now = new Date();
	queryform.byear.value = now.getYear();
	queryform.bmonth.value = now.getMonth()+1;
	queryform.bday.value = now.getDate();

	queryform.eyear.value = now.getYear();
	queryform.emonth.value = now.getMonth()+1;
	queryform.eday.value = now.getDate();
}
function changeYesterday(queryform)
{
	// 昨天
	var now = new Date();
	now.setDate( now.getDate()-1 );

	queryform.byear.value = now.getYear();
	queryform.bmonth.value = now.getMonth()+1;
	queryform.bday.value = now.getDate();

	queryform.eyear.value = now.getYear();
	queryform.emonth.value = now.getMonth()+1;
	queryform.eday.value = now.getDate();
}
function changeMonth(queryform)
{	// 本月
	var now = new Date();
	queryform.byear.value = now.getYear();
	queryform.bmonth.value = now.getMonth()+1;
	queryform.bday.value = 1;

	queryform.eyear.value = now.getYear();
	queryform.emonth.value = now.getMonth()+1;
	queryform.eday.value = now.getDate();
}

function changePreviousmonth(queryform)
{	// 上个月
	var now = new Date();
	var previousmonth = new Date();
	previousmonth.setMonth( now.getMonth()-1 );
	
	queryform.byear.value = previousmonth.getYear();
	queryform.bmonth.value = previousmonth.getMonth()+1;
	queryform.bday.value = 1;

	queryform.eyear.value = previousmonth.getYear();
	queryform.emonth.value = previousmonth.getMonth()+1;
	
	switch( previousmonth.getMonth()+1 )
	{
		case 1:
		case 3:
		case 5:
		case 6:
		case 8:
		case 10:
		case 12:
			queryform.eday.value = 31;
			break;
		case 4:
		case 6:
		case 9:
		case 11:
			queryform.eday.value = 30;
			break;
		case 2:
			if( isLeapyear(previousmonth.getYear()) )
				queryform.eday.value = 29;
			else
				queryform.eday.value = 28;
			break;
	}
}

function changeLastweek(queryform)
{	// 最近一周
	var now = new Date();
	var lastweek = new Date();
	lastweek.setDate( now.getDate()-6 );
	
	queryform.byear.value = lastweek.getYear();
	queryform.bmonth.value = lastweek.getMonth()+1;
	queryform.bday.value = lastweek.getDate();

	queryform.eyear.value = now.getYear();
	queryform.emonth.value = now.getMonth()+1;
	queryform.eday.value = now.getDate();
}

function changeLastmonth(queryform)
{	// 最近一月
	var now = new Date();
	var lastmonth = new Date();
	lastmonth.setDate( now.getDate()-30 );
	
	queryform.byear.value = lastmonth.getYear();
	queryform.bmonth.value = lastmonth.getMonth()+1;
	queryform.bday.value = lastmonth.getDate();

	queryform.eyear.value = now.getYear();
	queryform.emonth.value = now.getMonth()+1;
	queryform.eday.value = now.getDate();
}

function isLeapyear( year )
{
	if( year%400==0 ) return true;
	
	if( year%4==0 && year%100!=0 ) return true;
	else false;
}