function DateAdd(objDate, strInterval, intIncrement)
    {
        if(typeof(objDate) == "string")
        {
            objDate = new Date(objDate);
 
            if (isNaN(objDate))
            {
                throw("DateAdd: Date is not a valid date");
            }
        }
        else if(typeof(objDate) != "object" || objDate.constructor.toString().indexOf("Date()") == -1)
        {
            throw("DateAdd: First parameter must be a date object");
        }
 
        if(
        strInterval != "M"
        && strInterval != "D"
        && strInterval != "Y"
        && strInterval != "h"
        && strInterval != "m"
        && strInterval != "uM"
        && strInterval != "uD"
        && strInterval != "uY"
        && strInterval != "uh"
        && strInterval != "um"
        && strInterval != "us"
        )
        {
            throw("DateAdd: Second parameter must be M, D, Y, h, m, uM, uD, uY, uh, um or us");
        }
 
        if(typeof(intIncrement) != "number")
        {
            throw("DateAdd: Third parameter must be a number");
        }
 
        switch(strInterval)
        {
            case "M":
            objDate.setMonth(parseInt(objDate.getMonth()) + parseInt(intIncrement));
            break;
 
            case "D":
            objDate.setDate(parseInt(objDate.getDate()) + parseInt(intIncrement));
            break;
 
            case "Y":
            objDate.setYear(parseInt(objDate.getYear()) + parseInt(intIncrement));
            break;
 
            case "h":
            objDate.setHours(parseInt(objDate.getHours()) + parseInt(intIncrement));
            break;
 
            case "m":
            objDate.setMinutes(parseInt(objDate.getMinutes()) + parseInt(intIncrement));
            break;
 
            case "s":
            objDate.setSeconds(parseInt(objDate.getSeconds()) + parseInt(intIncrement));
            break;
 
            case "uM":
            objDate.setUTCMonth(parseInt(objDate.getUTCMonth()) + parseInt(intIncrement));
            break;
 
            case "uD":
            objDate.setUTCDate(parseInt(objDate.getUTCDate()) + parseInt(intIncrement));
            break;
 
            case "uY":
            objDate.setUTCFullYear(parseInt(objDate.getUTCFullYear()) + parseInt(intIncrement));
            break;
 
            case "uh":
            objDate.setUTCHours(parseInt(objDate.getUTCHours()) + parseInt(intIncrement));
            break;
 
            case "um":
            objDate.setUTCMinutes(parseInt(objDate.getUTCMinutes()) + parseInt(intIncrement));
            break;
 
            case "us":
            objDate.setUTCSeconds(parseInt(objDate.getUTCSeconds()) + parseInt(intIncrement));
            break;
        }
        return objDate;
    }