HTML调用Js的函数只显示函数名

function aaa()
{
var now=new Date();
var year = now.getFullYear();
var now = new Date();
var month = now.getMonth();
var now=new Date();
var day1=now.getDay();
var day;
switch(day1)
{
    case 1:
    day="星期一";
    break;
    case 2:
    day="星期二";
    break;
    case 3:
    day="星期三";
    break;
    case 4:
    day="星期四";
    break;
    case 5:
    day="星期五";
    break;
    case 6:
    day="星期六";
    break;
    case 7:
    day="星期日";
    break;
}
document.write(year);
document.write("/");
document.write(month);
document.write("/");
document.write(day1);
document.write("   ");
document.write(day);
}