根据年月日获取星期几

let wekks=this.getweekday('2021-03-28');

console.log(wekks);//输出‘日’

function getweekday(date){
    var weekArray = new Array("日", "一", "二", "三", "四", "五", "六");
    var week = weekArray[new Date(date).getDay()];//注意此处必须是先new一个Date
    return week;
 }