set cell content after new selection in a different cell

I’d like to update a cell with a new part description when the user has selected a new part number in another cell. Do I need to setup a custom event when the part number cell changes? Are there examples of doing this somewhere?

Could you clarify?

the user has selected a new part number in another cell
did you mean the selecting new option in the select/combo?

In that case you may use the onEditCell event. It will occur on changing the value of the cell:
docs.dhtmlx.com/api__dhtmlxgrid_ … event.html

I’d like to update a cell with a new part description
did you mean the changing of the cell value?

In that case you may use the setValue() method:
mygrid.cellById(row_id,col_ind).setValue(“new value”)