js獲取今天是周幾

function getMyDay(date){
var week;
if(date.getDay()==0) week="週日"
if(date.getDay()==1) week="週一"
if(date.getDay()==2) week="週二"
if(date.getDay()==3) week="週三"
if(date.getDay()==4) week="週四"
if(date.getDay()==5) week="週五"
if(date.getDay()==6) week="週六"
return week;
}

var w1 = getMyDay(new Date("2015-7-12"));


//指定的時間判斷是周幾
new Date('2019-08-27').getDay()---》得到2，表示週二

如果想要獲取到今天是周幾，則 
new Date().getDay()---》獲取到今天是周幾