JavaScript 格式化日期(任意格式)

//格式化日期
        Date.prototype.format = function(format) {
        var date = {
                "M+": this.getMonth() + 1,
                "d+": this.getDate(),
                "h+": this.getHours(),
                "m+": this.getMinutes(),
                "s+": this.getSeconds(),
                "q+": Math.floor((this.getMonth() + 3) / 3),
                "S+": this.getMilliseconds()
        };
        if (/(y+)/i.test(format)) {
                format = format.replace(RegExp.$1, (this.getFullYear() + '').substr(4 - RegExp.$1.length));
        }
        for (var k in date) {
                if (new RegExp("(" + k + ")").test(format)) {
                        format = format.replace(RegExp.$1, RegExp.$1.length == 1
                                ? date[k] : ("00" + date[k]).substr(("" + date[k]).length));
                }
        }
        return format;
        }