js计算系统当前日期是星期几的几种方法

方法一：

// 计算系统当前是星期几
var str = "今天是星期" + "日一二三四五六".charat(new Date().getDay());

方法二：

var a = new array("日", "一", "二", "三", "四", "五", "六");
var week = new Date().getDay();
var str = "今天是星期"+ a[week];
alert(str);

方法三：

var str = "今天是星期";
var week = new Date().getDay();
switch (week) {
        case 0 :
                str += "日";
                break;
        case 1 :
                str += "一";
                break;
        case 2 :
                str += "二";
                break;
        case 3 :
                str += "三";
                break;
        case 4 :
                str += "四";
                break;
        case 5 :
                str += "五";
                break;
        case 6 :
                str += "六";
                break;
}
alert(str);

方法四：

var str = "";
var week = new Date().getDay();
if (week == 0) {
        str = "今天是星期日";
} else if (week == 1) {
        str = "今天是星期一";
} else if (week == 2) {
        str = "今天是星期二";
} else if (week == 3) {
        str = "今天是星期三";
} else if (week == 4) {
        str = "今天是星期四";
} else if (week == 5) {
        str = "今天是星期五";
} else if (week == 6) {
        str = "今天是星期六";
}
alert(str);

当然这四种方法的完美程度是一目了然的。