Fetch records from grid

How can one fetch all records from jqgrid which satisfies specified condition? What I am trying to do is I had got one method ExportDataToExcel(Referred from: http://www.codeproject.com/Articles/784342/Export-data-from-jqGrid-into-a-real-Excel-file). I want to pass table created at runtime rather then jqgrid, since jqgrid only picks record displayed on a single page rather then all records on multiple page.