js根据日期获得星期

var weekday = getWeekday('2013-9-26');
function getWeekday(sDate){
        var dt = new Date(sDate.replace(/-/g, '/'));
        var a = ['星期日', '星期一','星期二','星期三','星期四','星期五','星期六'];
        return a[dt.getDay()];
    }