想用库还是想自己生转？用库的话：moment就挺好

自己生转，可以简单粗暴如下：

var str = '2016-1-9 12:12:20';
var ss = str.replace(/-([0-9]+)/g, function(match, p) {
    return p.length !== 1 ? match : '-0' + p;
});

console.log(ss); //2016-01-09 12:12:20

判断一下月和日，如果小于10,前面补一个0，小时分秒也是这样

"2016-1-9 12：12:20".replace(/-(\d)(?=-|\s)/g, '-0$1')

你前面的是什么格式的时间啊。。。。。没明白

你可以用moment.js 前端引入后直接转

试试这个,希望对你有帮助

function getNowFormatDate() {
    var date = new Date();
    var seperator1 = "-";
    var seperator2 = ":";
    var month = date.getMonth() + 1;
    var strDate = date.getDate();
    if (month >= 1 && month <= 9) {
        month = "0" + month;
    }
    if (strDate >= 0 && strDate <= 9) {
        strDate = "0" + strDate;
    }
    var currentdate = date.getFullYear() + seperator1 + month + seperator1 + strDate
            + " " + date.getHours() + seperator2 + date.getMinutes()
            + seperator2 + date.getSeconds();
    return currentdate;
}

<script type="text/javascript">

    function getNowDate() {
        var seper1 = "-";
        var seper2 = ":";
        var date = new Date();
        var year = date.getFullYear();
        var month = date.getMonth() + 1;
        var day = date.getDate();
        var hours = date.getHours();
        var minutes = date.getMinutes();
        var seconds = date.getSeconds();
        if (month >= 1 && month <= 9) {
            month = "0" + month;
        }
        if (day >= 0 && day <= 9) {
            day = "0" + day;
        }        
        if (hours >= 0 && hours <= 9) {
            hours = "0" + hours;
        }        
        if (minutes >= 0 && minutes <= 9) {
            minutes = "0" + minutes;
        }
        if (seconds >= 0 && seconds <= 9) {
            seconds = "0" + seconds;
        }
        var time = year + seper1 + month + seper1 + day + " " + hours + seper2 + minutes + seper2 + seconds;
        return time;
    }
    var p = document.createElement('p');
    p.innerHTML = getNowDate();
    setInterval(function(){
        p.innerHTML = getNowDate();
    },1000)
    document.getElementsByTagName('body')[0].appendChild(p);
</script>