一）

Date.prototype.Format = function (fmt) {
var o = {
"M+": this.getMonth() + 1, //月份
"d+": this.getDate(), //日
"H+": this.getHours(), //小时
"m+": this.getMinutes(), //分
"s+": this.getSeconds(), //秒
"q+": Math.floor((this.getMonth() + 3) / 3), //季度
"S": this.getMilliseconds() //毫秒
};
if (/(y+)/.test(fmt)) fmt = fmt.replace(RegExp.$1, (this.getFullYear() + "").substr(4 - RegExp.$1.length));
for (var k in o)
if (new RegExp("(" + k + ")").test(fmt)) fmt = fmt.replace(RegExp.$1, (RegExp.$1.length == 1) ? (o[k]) : (("00" + o[k]).substr(("" + o[k]).length)));
return fmt;
}

二）

function getFormatDate(){
var nowDate = new Date();
var year = nowDate.getFullYear();
var month = nowDate.getMonth() + 1 < 10 ? "0" + (nowDate.getMonth() + 1) : nowDate.getMonth() + 1;
var date = nowDate.getDate() < 10 ? "0" + nowDate.getDate() : nowDate.getDate();
var hour = nowDate.getHours()< 10 ? "0" + nowDate.getHours() : nowDate.getHours();
var minute = nowDate.getMinutes()< 10 ? "0" + nowDate.getMinutes() : nowDate.getMinutes();
var second = nowDate.getSeconds()< 10 ? "0" + nowDate.getSeconds() : nowDate.getSeconds();
return year + "-" + month + "-" + date+" "+hour+":"+minute+":"+second;
}
var str = getFormatDate();
console.log(str);

function getFormatDate(){
var nowDate = new Date();
var year = nowDate.getFullYear();
var month = nowDate.getMonth() + 1 < 10 ? "0" + (nowDate.getMonth() + 1) : nowDate.getMonth() + 1;
var date = nowDate.getDate() < 10 ? "0" + nowDate.getDate() : nowDate.getDate();
// var hour = nowDate.getHours()< 10 ? "0" + nowDate.getHours() : nowDate.getHours();
// var minute = nowDate.getMinutes()< 10 ? "0" + nowDate.getMinutes() : nowDate.getMinutes();
// var second = nowDate.getSeconds()< 10 ? "0" + nowDate.getSeconds() : nowDate.getSeconds();
return year + "-" + month + "-" + date;
}
var str = getFormatDate();
console.log(str);