js获得当前日期和昨天日期

function getSysDate(){

	var today = new Date();   
    var day   = today.getDate();                     
    var month = today.getMonth() + 1;   
    var year  = today.getYear();   
    var hours = today.getHours();   
    var minute = today.getMinutes();
//获取昨天的日期
	var zt = new Date(today.getYear(),today.getMonth(),today.getDate()-1);       
    month = month<10?"0"+month:month;//如果小于10即显示为09月     
    day = day<10?"0"+day:day;//如果小于10即显示为09日       
	var zt_Month = zt.getMonth()*1+1;
	var zt_date = zt.getDate();
	zt_Month = zt_Month<10?"0"+zt_Month:zt_Month;
	zt_date = zt_date<10?"0"+zt_date:zt_date;        
    document.getElementById('year1').value = zt.getYear();
	document.getElementById('year2').value = year;
	document.getElementById('month1').value = zt_Month;
	document.getElementById('month2').value = month;
	document.getElementById('day1').value = zt_date;
	document.getElementById('day2').value = day;
	document.getElementById('hour1').value = '00';
	document.getElementById('hour2').value = '00';
	document.getElementById('minute1').value = '00';
	document.getElementById('minute2').value = '00';
	var date = year + "-" + month + "-" + day + " "+hours +":"+minute;  
	//alert('---'+date);
	return date;
}