JS類似PHPのフォーマット時間

Date.prototype.format =function(format)
    {
        var o = {
        "M+" : this.getMonth()+1, //month
"d+" : this.getDate(),    //day
"h+" : this.getHours(),   //hour
"m+" : this.getMinutes(), //minute
"s+" : this.getSeconds(), //second
"q+" : Math.floor((this.getMonth()+3)/3),  //quarter
"S" : this.getMilliseconds() //millisecond
        }
        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 d =new Date().format('yyyy-MM-dd');