var day = Date.getDay();//拿到今天的日期，取值0-6，代表星期天到星期六
switch (day) {
            case 1:
                console.log("星期一")
                break;
            case 2:
                console.log("星期二")
                break;
            case 3:
                console.log("星期三")
                break;
            case 4:
                console.log("星期四")
                break;
            case 5:
                console.log("星期五")
                break;
            case 6:
                console.log("星期六")
                break;
            default:
                console.log("星期天")
                break;
        }
        
//if
if(day==0){
            console.log("今天是星期天")
        }else if(day==1){
            console.log("今天是星期一")
        }else if(day==2){
            console.log("今天是星期二")
        }else if(day==3){
            console.log("今天是星期三")
        }else if(day==4){
            console.log("今天是星期四")
        }else if(day==5){
            console.log("今天是星期五")
        }else(day==6){
            console.log("今天是星期六")
        }