獲取今天和昨天的日期及星期

	//獲取日期
	function getDaynum(num, str) {
       		var today = new Date();
       		var nowTime = today.getTime(); 
       		var ms = 24*3600*1000*num; 
       
       		today.setTime(parseInt(nowTime + ms)); 
       
     		  var oYear = today.getFullYear(); 
       
      		 var oMoth = (today.getMonth() + 1).toString(); 
       				if (oMoth.length <= 1) 
       				oMoth = '0' + oMoth; 
       		
       		var oDay = today.getDate().toString(); 
       
       				if (oDay.length <= 1) 
       				oDay = '0' + oDay;
       
       		return oYear + str + oMoth + str + oDay; 
       	
       		}
       	//獲取星期幾
       	function getWeek(dateString){  
		    var date;  
		    var dateArray = dateString.split("-");  
		    date = new Date(dateArray[0], parseInt(dateArray[1] - 1), dateArray[2]);  
		    return "星期" + "日一二三四五六".charAt(date.getDay());  
		};
	//今天
	 var today = getWeek(getDaynum(-0, '-'));  
	//昨天 
	 var yestday = getWeek(getDaynum(-1, '-'));