根据日期判断星期几

function getMyDay(date){
    var week;
    if(date.getDay()==0) week="星期日"
    if(date.getDay()==1) week="星期一"
    if(date.getDay()==2) week="星期二"
    if(date.getDay()==3) week="星期三"
    if(date.getDay()==4) week="星期四"
    if(date.getDay()==5) week="星期五"
    if(date.getDay()==6) week="星期六"
    return week;
}
var weeks = getMyDay(new Date("2017-09-25"));
console.log(weeks);