输出星期
    var myDate=new Date();
    var week=myDate.getDay();
    var str=‘今天是‘;
    switch (week) {
            case 1:
            str+=‘星期一‘
            break;        
            case 2:
            str+=‘星期二‘
            break;        
            case 3:
            str+=‘星期三‘
            break;        
            case 4:
            str+=‘星期四‘
            break;
            case 5:
            str+=‘星期五‘
            break;
            case 6:
            str+=‘星期六‘
            break;
            default:
            str+=‘星期天‘
            break;
    }
     document.writeln(str);