getDay()返回星期，返回的是0-6的數字，0 表示星期天。用數組weekday[]存儲“星期一”到“星期日”，

var weekday=["星期日","星期一","星期二","星期三","星期四","星期五","星期六"];

??? 代表著weekday[0]="星期日"，weekday[1]="星期一"，weekday[2]="星期二"，weekday[3]="星期三"，weekday[4]="星期四"，weekday[5]="星期五"，weekday[6]="星期六"。

用getDay()返回星期，返回的數字傳給數組獲取下標，通過下標找到對應的數組元素，用document.write輸出數組元素。例如：getDay()返回的數字是6，對應數組下標6，weekday[6]=“星期六”。