js获取昨天日期

刚刚js做项目,遇到需要获取昨天日期的问题,网上找了下答案,感觉网上的答案都不太严谨,自己写了个,凑合能用吧,忘大神们抛砖指教.

<script type="text/javascript" language="javascript">
    function getYestoday(date){
        var arrMonth = new Array([], [], [], [], [], [], [], [], [], [], [], [], []);//初始化月份(第一个0,占位作用,让下标和月份对应)
        var strYear = date.getFullYear();//获取年份
        var strDay = date.getDate();//获取日期
        var strMonth = date.getMonth() + ;//获取月份
        ///判断是否是闰年
        if (strYear %  ==  && strYear %  != ) {
            arrMonth[] = ;
        }
        ///判断日期是否是第一天
        if (strDay -  == ) {
            ///判断月份是否是一月
            if (strMonth -  == ) {
                strYear -= ;
                strMonth = ;
            } else {
                strMonth -= ;
            }
            strDay = arrMonth[strMonth];
        } else {
            strDay -= ;
        }
        ///月份小于10,前面加0
        if (strMonth < ) {
            strMonth = "" + strMonth;
        }
        ///日期小于10,前面加0
        if (strDay < ) {
            strDay = "" + strDay;
        }
        return strYear + "-" + strMonth + "-" + strDay;
    }
    alert(getYestoday(new Date("2012-1-1")));//测试日期
</script>