format方法格式化Date时间日期

<script>
Date.prototype.format = function(format) {
if (isNaN(this)) return '';
var o = {
'm+': this.getMonth() + 1,
'd+': this.getDate(),
'h+': this.getHours(),
'n+': this.getMinutes(),
's+': this.getSeconds(),
'S': this.getMilliseconds(),
'W': ["日", "一", "二", "三", "四", "五", "六"][this.getDay()],
'q+': Math.floor((this.getMonth() + 3) / 3)
};
if (format.indexOf('am/pm') >= 0) {
format = format.replace('am/pm', (o['h+'] >= 12) ? '下午' : '上午');
if (o['h+'] >= 12) o['h+'] -= 12;
}
if (/(y+)/.test(format)) {
format = format.replace(RegExp.$1, (this.getFullYear() + "").substr(4 - RegExp.$1.length));
}
for (var k in o) {
if (new RegExp("(" + k + ")").test(format)) {
format = format.replace(RegExp.$1, RegExp.$1.length == 1 ? o[k] : ("00" + o[k]).substr(("" + o[k]).length));
}
}
return format;
}
var time = new Date().format('yyyy-mm-dd hh-nn-ss am/pm');
alert("现在是"+time);

</script>