This method initiates a file download of the grid data. The call to this method can be attached to a button or a similar element's onclick event to initiate the download manually instead of using the "csv export" property on the grid, which creates a paging bar with an export link. The data is output in CSV (Comma Separated Values) format. If the grid's "export with headings" property is set to true, grid headings are exported in addition to the grid data.
file - specifies the default file name given to the CSV file (Optional); the file extension should not be part of this name since ".csv" is automatically appended; if the file name parameter is omitted, the id of the grid is used