DataTable to JSON

public static class JSONHelper
{
    public static string FromDataTable(DataTable dt)
    {
        string rowDelimiter = "";

        StringBuilder result = new StringBuilder("[");
        foreach (DataRow row in dt.Rows)
        {
            result.Append(rowDelimiter);
            result.Append(FromDataRow(row));
            rowDelimiter = ",";
        }
        result.Append("]");

        return result.ToString();
    }

    public static string FromDataRow(DataRow row)
    {
        DataColumnCollection cols = row.Table.Columns;
        string colDelimiter = "";

        StringBuilder result = new StringBuilder("{");
        for (int i = 0; i < cols.Count; i++)
        { // use index rather than foreach, so we can use the index for both the row and cols collection
            result.Append(colDelimiter).Append(""")
                  .Append(cols[i].ColumnName).Append("":")
                  .Append(JSONValueFromDataRowObject(row[i], cols[i].DataType));

            colDelimiter = ",";
        }
        result.Append("}");
        return result.ToString();
    }

    // possible types:
    // http://msdn.microsoft.com/en-us/library/system.data.datacolumn.datatype(VS.80).aspx
    private static Type[] numeric = new Type[] {typeof(byte), typeof(decimal), typeof(double),
                                     typeof(Int16), typeof(Int32), typeof(SByte), typeof(Single),
                                     typeof(UInt16), typeof(UInt32), typeof(UInt64)};

    // I don't want to rebuild this value for every date cell in the table
    private static long EpochTicks = new DateTime(1970, 1, 1).Ticks;

    private static string JSONValueFromDataRowObject(object value, Type DataType)
    {
        // null
        if (value == DBNull.Value) return "null";

        // numeric
        if (Array.IndexOf(numeric, DataType) > -1)
            return value.ToString(); // TODO: eventually want to use a stricter format

        // boolean
        if (DataType == typeof(bool))
            return ((bool)value) ? "true" : "false";

        // date -- see http://weblogs.asp.net/bleroy/archive/2008/01/18/dates-and-json.aspx
        if (DataType == typeof(DateTime))
            return ""\/Date(" + new TimeSpan(((DateTime)value).ToUniversalTime().Ticks - EpochTicks).TotalMilliseconds.ToString() + ")\/"";

        // TODO: add Timespan support
        // TODO: add Byte[] support

        //TODO: this would be _much_ faster with a state machine
        // string/char
        return """ + value.ToString().Replace(@"", @"\").Replace(Environment.NewLine, @"n").Replace(""", @"""") + """;
    }
}