时间格式包装

   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;
}