javascript format Date 简单的时间格式化

<script type="text/javascript">
var formatDate = function (formatDate, formatString) {
    if(formatDate instanceof Date) {
        var months = new Array("Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec");
        var yyyy = formatDate.getFullYear();
        var yy = yyyy.toString().substring(2);
        var m = formatDate.getMonth();
        var mm = m < 10 ? "0" + m : m;
        var mmm = months[m];
        var d = formatDate.getDate();
        var dd = d < 10 ? "0" + d : d;

        var h = formatDate.getHours();
        var hh = h < 10 ? "0" + h : h;
        var n = formatDate.getMinutes();
        var nn = n < 10 ? "0" + n : n;
        var s = formatDate.getSeconds();
        var ss = s < 10 ? "0" + s : s;

        formatString = formatString.replace(/yyyy/i, yyyy);
        formatString = formatString.replace(/yy/i, yy);
        formatString = formatString.replace(/mmm/i, mmm);
        formatString = formatString.replace(/mm/i, mm);
        formatString = formatString.replace(/m/i, m);
        formatString = formatString.replace(/dd/i, dd);
        formatString = formatString.replace(/d/i, d);
        formatString = formatString.replace(/hh/i, hh);
        formatString = formatString.replace(/h/i, h);
        formatString = formatString.replace(/nn/i, nn);
        formatString = formatString.replace(/n/i, n);
        formatString = formatString.replace(/ss/i, ss);
        formatString = formatString.replace(/s/i, s);

        return formatString;
    } else {
        return "";
    }

}
</pre>

This will  show a demo date 

<pre lang="javascript">
alert(formatDate(new Date(), "d mmm yyyy hh:nn:ss"));