This is a FAQ on Stack Overflow ---> How can I test a trigger function in GAS?

on the other side, the changeType property belongs to the change event, not to the form submit event.

According to Serge Insas, "to know what value is returned in the event info" instead of event.changeType use Utilities.jsonStringify(event).

References

• Event Objects - Google Apps Script
• Google Apps Event changeType undefined in Google Sheet - Stack Overflow

You can modify the function params to accept the argument it's given, and use it in forming the string that it returns. Like so:

function params(row) {                                   // added row here
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var ssid = ss.getId();
  var sheet = ss.getActiveSheet();
  var sheetName = sheet.getName();
  return '?ssid='+ssid+'&name='+sheetName+'&row='+row;   // added row here
}

Now when you use ...exec" & params(1)) the value of 1 will be correctly appended to the URL used to invoke the web app: the URL will have &row=1 and consequently, the doGet function of the web app will receive this value as e.parameters.row.

However it's easier to just append 1 yourself: in the hyperlink function, put

...exec" & params() & "&row=1" )

or

...exec" & params() & "&row=" & row() )

There is no need to run a number through a custom function when you can just append it to the URL in the spreadsheet. The reason the custom function params is needed is to pass the values that spreadsheet functions cannot access: spreadsheet id and sheet name.