Filter.cs

public void Filter(string columnName, FilterOperator filterOperator, string filterValue)
{
    this.Filter(new GridFilter(columnName, filterOperator, filterValue));
}

public void Filter(params GridFilter[] gridFilters)
{
    string jsToBeExecuted = this.GetGridReference();
    StringBuilder sb = new StringBuilder();
    sb.Append(jsToBeExecuted);
    sb.Append("grid.dataSource.filter({ logic: \"and\", filters: [");
    foreach (var currentFilter in gridFilters)
    {
        DateTime filterDateTime;
        bool isFilterDateTime = DateTime.TryParse(currentFilter.FilterValue, out filterDateTime);
        string filterValueToBeApplied =
                                        isFilterDateTime ? string.Format("new Date({0}, {1}, {2})", filterDateTime.Year, filterDateTime.Month - 1, filterDateTime.Day) :
                                        string.Format("\"{0}\"", currentFilter.FilterValue);
        string kendoFilterOperator = this.ConvertFilterOperatorToKendoOperator(currentFilter.FilterOperator);
        sb.Append(string.Concat("{ field: \"", currentFilter.ColumnName, "\", operator: \"", kendoFilterOperator, "\", value: ", filterValueToBeApplied, " },"));
    }
    sb.Append("] });");
    jsToBeExecuted = sb.ToString().Replace(",]", "]");
    this.driver.ExecuteScript(jsToBeExecuted);
}

private string ConvertFilterOperatorToKendoOperator(FilterOperator filterOperator)
{
    string kendoFilterOperator = string.Empty;
    switch (filterOperator)
    {
        case FilterOperator.EqualTo:
            kendoFilterOperator = "eq";
            break;
        case FilterOperator.NotEqualTo:
            kendoFilterOperator = "neq";
            break;
        case FilterOperator.LessThan:
            kendoFilterOperator = "lt";
            break;
        case FilterOperator.LessThanOrEqualTo:
            kendoFilterOperator = "lte";
            break;
        case FilterOperator.GreaterThan:
            kendoFilterOperator = "gt";
            break;
        case FilterOperator.GreaterThanOrEqualTo:
            kendoFilterOperator = "gte";
            break;
        case FilterOperator.StartsWith:
            kendoFilterOperator = "startswith";
            break;
        case FilterOperator.EndsWith:
            kendoFilterOperator = "endswith";
            break;
        case FilterOperator.Contains:
            kendoFilterOperator = "contains";
            break;
        case FilterOperator.NotContains:
            kendoFilterOperator = "doesnotcontain";
            break;
        case FilterOperator.IsAfter:
            kendoFilterOperator = "gt";
            break;
        case FilterOperator.IsAfterOrEqualTo:
            kendoFilterOperator = "gte";
            break;
        case FilterOperator.IsBefore:
            kendoFilterOperator = "lt";
            break;
        case FilterOperator.IsBeforeOrEqualTo:
            kendoFilterOperator = "lte";
            break;
        default:
            throw new ArgumentException("The specified filter operator is not supported.");
    }

    return kendoFilterOperator;
}