input.type = “number”; but only for specific input field

How I can use my : input.type = "number"; to be used only in specific fields?

            var cell1 = row.insertCell(0);
            var cell2 = row.insertCell(1);
            var cell3 = row.insertCell(2);
            var cell4 = row.insertCell(3); 

I have these inserts, to insert fields into the table. So how can I specify only for the eg. Cell(0)? To have only numbers (0-9) in the specific fields.

Sorry if sounds stupid.
Thank you