[рони]

dany2855,

function Time(str) {
    var objTime = {
        init: function(str) {
            var arr = str.split(/[\s:-]/);
            this.newDate = new Date(Date.UTC(arr[0], arr[1] - 1, arr[2], arr[3], arr[4], 0, 0));
            return this;
        },
        add: function(value, string) {
            if (string in this.method) {
                return this.setValue(value, this.method[string]);
            } else {
                throw new Error("Передано неверное значение: " + string);
            }
        },
        method: {
            "years": "FullYear",
            "months": "Month",
            "days": "Date",
            "hours": "Hours",
            "minutes": "Minutes"
        },
        setValue: function(value, method) {
            this.newDate["setUTC" + method](value + this.newDate["getUTC" + method]());
            return this;
        },
        substract: function(value, string) {
            return this.add(-value, string);
        },
        toString: function() {
          return this.newDate.toLocaleString("ru",{timeZone : "UTC"});
        },
        valueOf: function() {
            return +this.newDate
        }
    };
    return objTime.init(str);
};

var str = "2012-01-11 12:35";
var time = new Time(str);
time.add(24, "hours").substract(1, "months").add(3, "days").add(15, "minutes");
alert(time);
alert(+time);