js扩展日期

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');